Recycling, Volume 1, Issue 1 (June 2016) – 15 articles , Pages 1-218

Composites of recycled high-density polyethylene and micro fibres of sugarcane bagasse were studied, in order to create an upcycled material to produce masonry bricks. We ranged the polymer/filler ratio from 100–0 to 60%–40%. The materials were assessed through scanning electron microscopy, thermogravimetry/derivative thermogravimetry, differential scanning calorimetry, rheological measurements and compressive strength test. The composites showed a good dispersion and adhesion of the filler into the polymeric matrix. There was no significant variation on the melting and crystallizing temperatures of the materials if compared to those of neat polymer, indicating that there was no relevant change in the average size of the polymeric crystals. We assumed that some transcrystallization has happened, because the degree of crystallinity of the composites increased to all filler contents, while the crystallizing temperature remained the same. There was a rise in the compressive moduli of the composites, ranging from 37% to 63%. The modulus at the crossover point and the complex viscosity also rose due to the fibres ratio. The results show that the combination of these materials led to the reinforcement of the compressive strength of the polymer, and have interesting properties as a potential building material. Full article

A novel natural low transition temperature mixture (LTTM), composed of glycerol and ammonium acetate (molar ratio 3:1), was tested for its efficacy as a solvent in recovering phenolics from chlorogenate-rich agri-food solid wastes, including potato peels (PPs), eggplant peels (EPPs), and spent filter coffee (SFC). The efficacy of this solvent was compared with other eco-friendly solvents, including aqueous glycerol, aqueous ethanol, and water. The LTTM was demonstrated to be by far the most efficient in extracting chlorogenates and superior or equally efficient with the other solvents in recovering flavonoids. LTTM extracts produced from waste were also more potent radical scavengers, but results on the reducing power were inconclusive. Liquid chromatography-diode array-mass spectrometry analysis showed that the polyphenolic profiles of all waste extracts obtained with the LTTM were rich in caffeoylquinic and p-coumaroylquinic acid conjugates. Full article

Worldwide volume production and consumption of engineered composite materials, namely fiber reinforced polymers (FRP), have increased in the last decades, mostly in the construction, automobile, aeronautic and wind energy sectors. This rising production and consumption have also led to an increasing amount of FRP waste, either end-of-life (EoL) products or manufacturing rejects. Taking into account the actual and impending EU framework on waste management, in which clear targets are set with concrete measures to ensure effective implementation, landfill and incineration will be progressively unavailable as traditional end-routes for this kind of waste. Recycling techniques and end-use applications for the recyclates have been investigated over the past twenty years, but even so, more cost-effective and feasible market outlets for the recyclates should be identified that meet both the economic and the environmental points of view. This paper is aimed at enclosing and summarizing an update overview regarding all these issues: current legislation, recycling techniques and end-use applications for the recyclates. Additionally, as a case study, the assessment of the potential improvements that could be made on the eco-efficiency performance (sustainability) of a typical FRP composite materials’ industry by recycling and re-engineering process approaches is also reported. Full article

Textile wastes in landfills are a major concern and offer wide scope in terms of waste management. The process of upcycling which aims at converting the waste into products of higher value is a feasible option. The research aims to explore factors to improve the process of upcycling. A set of mixed polyester/cotton (PES/CO) and cotton waste textiles from hospitals were examined for their properties. There are some physical parameters such as the mechanical properties and degree of polymerization that govern the process of upcycling. It was concluded that the textiles are degraded unevenly, so that it is difficult to predict their pattern of degradation. However, there are other possibilities and processes of using the waste textiles to reduce the waste in landfills. Full article

Household waste separation at the source is a central part of waste management systems in Sweden. Resource recovery of materials and energy increased substantially after separate collection was implemented in the 1990s. A procedure to transform recycling behavior for the sorting of household waste—called the recycling behavior transition (RBT) procedure—was designed and implemented in a waste management system in Sweden. Repeated use of this procedure, which will assist in the continual improvement of household sorting, consists of the following four consecutive steps: (i) evaluating the current sorting behavior; (ii) identifying appropriate interventions; (iii) implementing the interventions, and; (iv) assessing the quantitative effect of the interventions. This procedure follows action research methodology and it is the first time that such a procedure has been developed and implemented for the sorting of household waste. The procedure can easily be adapted to any source separation system (which may have different local situations) and, by improving the source separation, will increase the resource recovery in the waste management system. The RBT procedure, together with its strengths and weaknesses, is discussed in this paper, and its implementation is exemplified by a pilot study done in Sweden. Full article

This study undertook a critical examination of Ontario’s extended producer responsibility scheme for the residential “Blue Box” recycling program, specifically examining the relationship between packaging fee rates and material-specific recycling rates. Using data collected for each of the 23 materials found in the residential recycling program over the past decade, a regression model was developed to gauge what relationship (if any) packaging recycling rates have with fee rates, costs of material management and revenue from the sale of recyclable material. The modeling in this study indicates that packaging fee rates have no effect on packaging recycling rates. Recycling rates were positively correlated with material revenue and negatively correlated with material management costs. There is no evidence that suggests that Ontario’s fee model used to allocate environmental handling fees to individual materials encourages waste diversion or design for the environment. The disconnect in the results and the intended function of packaging fee rates calls into question the appropriateness of Ontario’s fee rate methodology. Full article

In order to secure valuable materials and to establish better circular economy practice, new legislation to promote recycling of small-sized e-waste including used mobile phones started in April 2013, in Japan. In order to consider appropriate methods to reduce material usage in mobile phone production, an examination of appropriate strategies in handling used mobile phone products is warranted. This paper investigates an analysis of material flow model for used mobile phones. Then, by analyzing the model, it tries to find suitable strategies to reduce the material consumption associated with mobile phone production and consumption. Although material recycling is an important strategy in Japan, other waste management options exist. This research indicates which factors are keys in reducing material consumption and CO₂ emission, and establishing resource efficient production. The study concludes that “domestic product reuse” and “official recycling networks” are equally good in reducing the consumption of virgin materials associated with mobile phone production. However, in doing so, it is necessary to establish a system in which consumers can properly return their used mobile phones for recycling. Such an end-of-life waste management system can reduce both waste and resource consumption and the environmental impacts associated with increasing mobile phone production. Further research investigating the value of increasing the product reuse rate and the collection return rate for mobile phones is also warranted. Full article

The treatment of lead-containing cathode-ray tube (CRT) glass is an important environmental issue. One approach is the removal of lead by chloride volatilization. In the present work, the reaction of CRT glass with PVC as the chlorinating agent and Ca(OH)₂ as the chlorine absorber was investigated by thermogravimetric analysis (TGA) in air. Seven reaction steps occurring at different temperatures were identified as dehydrochlorination of PVC/HCl absorption, CO₂ absorption, Ca(OH)₂ dehydration, PVC derived char oxidation, PbCl₂ formation and volatilization, CaCO₃ decarbonation, and CaCl₂ volatilization. Kinetic analysis of the PbCl₂ volatilization showed that the reaction of CRT glass during TGA resembles that of amorphous PbSiO₄, while the reaction in the tube reactor was similar to that of crystalline PbSiO₄. Crystallization accelerates PbCl₂ volatilization, and it might be advantageous for lead removal to crystallize the glass deliberately before or during treatment in order to reduce processing time and increase efficiency. Full article

Waste electrical and electronic equipment (WEEE) is growing rapidly, and the plastics within WEEE have an important role in fulfilling the recovery and recycling targets defined in the European WEEE Directive. This study considers recycling of WEEE plastics by making a blend of the different plastics instead of separating them. The mechanical and thermal properties can be enhanced by adding a compatibilizer. It was found that one compatibilizer, a styrene-b(ethylene-co-butylene)-b-styrene (SEBS) copolymer named Kraton^® G1652 E, had a large impact on the ductility of the recycled WEEE plastics blend. By adding 2.5 weight % (wt%) of this copolymer, the elongation at break increased by more than five times compared with the non-compatibilized samples, with only a small decrease in stiffness and strength. The storage modulus (G’) decreased slightly with increasing compatibilizer amounts while the impact strength increased with increasing amounts of compatibilizer, from 2.1 kJ/m² (reference material) to 3.6 kJ/m² (5 weight % (wt%) compatibilizer). It was found that Kraton^® FG1901 E (styrene-b(ethylene-co-butylene)-b-styrene (SEBS) grafted with maleic anhydride (MAH)), Royaltuf^® 372P20 (styrene acrylonitrile (SAN) modified with ethylene-propylene-diene elastomers (EPDM)) and Fusabond^® P353 (polypropylene (PP) with a high degree of grafted MAH) were ineffective as compatibilizers to the blend. Gamma irradiation (50 kGy) did not improve the mechanical properties however: the impact strength of the gamma-irradiated samples was lower than that of the non-irradiated samples. Full article

A melt-blended and melt-filtered real post-consumer and recyclable waste electrical and electronic equipment plastics blend (WEEEBR) was studied, where the WEEEBR contained mainly acrylonitrile-butadiene-styrene copolymer (~40 wt %), high impact polystyrene (~40 wt %) and polypropylene (~10 wt %). The main aim was to better understand the influence of different reprocessing conditions on the mechanical and thermal properties of WEEEBR and to compare these properties with the corresponding properties of model material blends of samples from single screw extrusion, twin screw extrusion and injection molding. For all the reprocessing alternatives studied, WEEEBR was found to be processable and an acceptable surface character could be obtained within narrow processing condition windows. It was found in particular that the reprocessing conditions influenced the elongation at break of WEEEBR, and to a lesser extent also the width of the polypropylene melting temperature region. The highest yield stress and elongation at break of WEEEBR was obtained after twin-screw extrusion at low barrel temperatures (180–200 °C) and a low screw rotation rate (60 rpm). Injection molding produced brittle materials with low impact strength, possibly due to molecular orientation effects. Full article

Household waste is a serious environmental problem in Indonesia, especially in urban areas. Since 2010, biogas production from food waste has been introduced to reduce waste and provided an alternative to liquid petroleum gas (LPG) as cooking fuel in a pilot project in Bandung. Although the produced biogas is sufficient, the socio-economic aspects can hinder application. This study assesses the socio-economic feasibility of the project in Cibangkong, a typical urban area in Bandung, which includes four bio-digesters. The results show that the conversion of food waste into biogas is currently not economically feasible, mainly due to the low penetration of bio-slurry—a by-product commonly used for fertilizer—into local fertilizer supply-chains. From a social perspective, community acceptance is mainly influenced by procedural justice. Furthermore, while the produced biogas is perceived to be quite useful in substituting LPG, it has not yet been fully utilized due to low bio gas pressure and several technical failures, which in turn influence community acceptance of the digesters. It is thus concluded that introducing biogas production from waste to improve waste management and reduce LPG consumption can be feasible when efforts to support the market uptake of bio-slurry, enhance biogas utilization, and improve procedural justice performance, are taken. Full article

The introduction of electromobility causes major challenges as new components and materials enter vehicle recycling. This paper discusses the current developments in the recycling of traction batteries, electric motors, and power electronics, which constitute the key components of (hybrid) electric vehicles. Both technical and ecological aspects are addressed. Beside base metals, all components contain metals that are considered critical by the EU (European Union), e.g., rare earth elements, cobalt, antimony, and palladium. As electromobility is a new trend, no recycling routes have been established at an industrial scale for these components. The implementation is complicated by small return flows and a great variety of vehicle concepts as well as components. Furthermore, drastic changes regarding design and material compositions can be expected over the next decades. Due to hazards and high weights, there is a strong research emphasis on battery recycling. Most pilot-scale or semi-industrial processes focus on the recovery of cobalt, nickel, and copper due to their high value. Electric motors and power electronics can be fed into established recycling routes if they are extracted from the vehicle before shredding. However, these processes are not capable of recovering some minor metals such as rare earth elements and antimony. Full article

Wood ash has been widely used as an additive for excreta from dry compost toilets to sanitize it for reuse. However, there is dearth of quantitative information about its efficiency in sanitizing partially digested sludge from wet onsite sanitation systems. This paper presents findings of a series of two experimental studies to assess optimum wood ash dosages required to raise the pH of partially digested fecal sludge to sanitizing levels (pH > 11) in a tropical climate. The study monitored the variation of pH of the sludge containing between 0 (control) and 180 g of ash per litre of sludge. Average initial pH and total solids of the sludge were 7.79 and 72 g/L respectively. Generally, the magnitude and rapidity of pH spike was correlated with the ash dosage (r = 0.988) and was statistically significant (p = 0.0015; F_crit = 2.3157) among all dosages. Drastic increase in pH (from 7.81 to 11.60 ± 0.07) was recorded in the first 24 h for ash dosages between 140 g/L and 180 g/L, whereas dosages below 140 g/L had pH values less than 10. The difference in variation of pH between the first 24 h and the successive 24 h was statistically significant (P(T ≤ t)_two-tail = 0.00; t_crit = 2.09). On the average, 97% of the overall pH increment within a 48-h monitoring period occurred in the first 24 h for the 140–180 g/L ash dosages. The optimum ash dosages are 7–15 times higher than reported lime dosages but ash provides a cheaper alternative than lime for recycling plant nutrients. Further studies on pathogen inactivation efficiency are ongoing. Full article

Support material used in constructed wetlands has been shown to be a key element and significant mechanism in the process of contaminants removal from sewage including phosphorus compounds. Recycled waste tires processed into small chips that are similar to conventional stone aggregate are currently used in the construction of septic system leach fields and could be a green alternative as support material in constructed wetlands. During three years, the performance of a gravity subsurface horizontal flow constructed wetland using recycled shredded-tire chips as support material to treat on-site the high strength wastewater from a bakery was monitored. Grab samples of the effluent from the septic tank and the constructed wetland were collected quarterly and submitted to a certified laboratory. Final treatment efficiency (percentage removal) was low for potassium (36%), intermediate for total nitrogen (56%), and total Kjeldahl nitrogen (57%), and relatively high for total phosphorus (65%), total suspended solids (69%), ammonia-nitrogen (87%), five-day biochemical oxygen demand (92%), Escherichia coli (97%), and fat-oil and grease total (99%). Nitrate-nitrogen final mean value was consistently below 1 mg/L, and iron concentration increased from less of 2 mg/L in the sewage to 55 mg/L in the constructed wetland effluent. These results show that recycled shredded-tire chips could be an environmental alternative support material in constructed wetlands as efficient removal of typical wastewater contaminants is not compromised. Full article

The potential to convert a waste or previously unutilised material as a reusable material will be of increasing importance in the 21st century as we see burgeoning population growth put further pressure on the world’s finite resources and waste management options. This proposition alone will see increasing economic and environmental benefits gained from recycling activities. The essential decoupling of economic growth and the depletion of non-renewable resources is one of the most significant challenges for sustainable development over the next century. This challenge involves reducing the total consumption of raw materials as well as developing further impetus for recycling and reuse activities to meet the increasing demand for materials.[...] Full article