| 1. |
- Andersson, Camilla, et al.
(författare)
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Direct and indirect effects of waste management policies on household waste behaviour : The case of Sweden
- 2018
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 76, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Swedish legislation makes municipalities responsible for recycling or disposing of household waste. Municipalities therefore play an important role in achieving Sweden’s increased levels of ambition in the waste management area and in achieving the goal of a more circular economy. This paper studies how two municipal policy instruments – weight-based waste tariffs and special systems for the collection of food waste – affect the collected volumes of different types of waste. We find that a system of collecting food waste separately is more effective overall than imposing weight-based waste tariffs in respect not only of reducing the amounts of waste destined for incineration, but also of increasing materials recycling and biological recovery, despite the fact that the direct incentive effects of these two systems should be similar. Separate food waste collection was associated with increased recycling not only of food waste but also of other waste. Introducing separate food waste collection indirectly signals to households that recycling is important and desirable, and our results suggest that this signalling effect may be as important as direct incentive effects.
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| 2. |
- Andersson, Magnus, 1983, et al.
(författare)
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Are scarce metals in cars functionally recycled?
- 2017
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 60, s. 407-416
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Tidskriftsartikel (refereegranskat)abstract
- Improved recycling of end-of-life vehicles (ELVs) may serve as an important strategy to address resource security risks related to increased global demand for scarce metals. However, in-depth knowledge of the magnitude and fate of such metals entering ELV recycling is lacking. This paper quantifies input of 25 scarce metals to Swedish ELV recycling, and estimates the extent to which they are recycled to material streams where their metal properties are utilised, i.e. are functionally recycled. Methodologically, scarce metals are mapped to main types of applications within newly produced Swedish car models and subsequently, material flow analysis of ELV waste streams is used as basis for identifying pathways of these applications and assessing whether contained metals are functionally recycled. Results indicate that, of the scarce metals, only platinum may be functionally recycled in its main application. Cobalt, gold, manganese, molybdenum, palladium, rhodium and silver may be functionally recycled depending on application and pathways taken. For remaining 17 metals, functional recycling is absent. Consequently, despite high overall ELV recycling rates of materials in general, there is considerable risk of losing ELV scarce metals to carrier metals, construction materials, backfilling materials and landfills. Given differences in the application of metals and identified pathways, prospects for increasing functional recycling are discussed.
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| 3. |
- André, Hampus, 1989, et al.
(författare)
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Resource and environmental impacts of using second-hand laptop computers: A case study of commercial reuse
- 2019
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 88, s. 268-279
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Tidskriftsartikel (refereegranskat)abstract
- The circular economy is proposed to reduce environmental impact, but as yet, there is limited empirical evidence of this sort from studying real, commercial circular economy business cases. This study investigates the environmental impacts of using second-hand laptops, mediated by a commercial reuse operation, instead of new ones. The method used is life cycle assessment (LCA) and special attention is given to laptops’ metal resource use by using several complementary life cycle impact assessment methods. The results show that all activities required to enable reuse of laptops are negligible, despite the reuse company’s large geographical scope. Two principal features of reuse reduce environmental impacts. Firstly, use extension reduces all impacts considerably since there are large embedded impacts in components. Secondly, the reuse company steers non-reusable laptops into state-of-the-art recycling. This provides additional impact reductions, especially with regards to toxicity and metal resource use. The results for metal resource use however diverge between LCIA methods in terms of highlighted metals which, in turn, affects the degree of impact reduction. LCIA methods that characterise functionally recycled metals as important, result in larger impact reduction, since these emphasise the merits of steering flows into state-of-the-art recycling. The study thus demonstrates how using second-hand laptops, mediated by a commercial reuse operation, compared to new ones, in practice, reduces different types of environmental impact through synergistic relationships between reuse and recycling. Moreover, it illustrates how the choice of LCIA method can influence interpretations of metal resource use impacts when applying circular economy measures to information and communication technologies (ICT).
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| 4. |
- Bernstad Saraiva, Anna, et al.
(författare)
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Lifecycle assessment of a system for food waste disposers to tank : A full-scale system evaluation
- 2016
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 54, s. 169-177
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Tidskriftsartikel (refereegranskat)abstract
- An increased interest for separate collection of household food waste in Sweden has led to development of a number of different collection-systems - each with their particular benefits and drawbacks. In the present study, two systems for collection of food waste in households were compared; (a) use of food waste disposers (FWD) in kitchen sinks and (b) collection of food waste in paper bags for further treatment. The comparison was made in relation to greenhouse gas emissions as well as primary energy utilization. In both cases, collected food waste was treated through anaerobic digestion and digestate was used as fertilizer on farmland. Systems emissions of greenhouse gases from collection and treatment of 1 ton of food waste (dry matter), are according to the performed assessment lower from the FWD-system compared to the reference system (-990 and -770 kg CO2-eq./ton food waste dry matter respectively). The main reasons are a higher substitution of mineral nitrogen fertilizer followed by a higher substitution of diesel. Performed uncertainty analyses state that results are robust, but that decreasing losses of organic matter in pre-treatment of food waste collected in paper bags, as well as increased losses of organic matter and nutrients from the FWD-system could change the hierarchy in relation to greenhouse gas emissions. Owing to a higher use of electricity in the FWD-system, the paper bag collection system was preferable in relation to primary energy utilization. Due to the many questions still remaining regarding the impacts of an increased amount of nutrients and organic matter to the sewage system through an increased use of FWD, the later treatment of effluent from the FWD-system, as well as treatment of wastewater from kitchen sinks in the reference system, was not included in the assessment. In future work, these aspects would be of relevance to monitor. (C) 2016 Elsevier Ltd. All rights reserved.
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| 5. |
- Carlsson, My, et al.
(författare)
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Impact of physical pre-treatment of source-sorted organic fraction of municipal solid waste on greenhouse-gas emissions and the economy in a Swedish anaerobic digestion system
- 2015
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 38, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- Several methods for physical pre-treatments of source sorted organic fraction of municipal solid waste (SSOFMSW) before for anaerobic digestion (AD) are available, with the common feature that they generate a homogeneous slurry for AD and a dry refuse fraction for incineration. The selection of efficient methods relies on improved understanding of how the pre-treatment impacts on the separation and on the slurry’s AD. The aim of this study was to evaluate the impact of the performance of physical pre-treatment of SSOFMSW on greenhouse-gas (GHG) emissions and on the economy of an AD system including a biogas plant with supplementary systems for heat and power production in Sweden. Based on the performance of selected Swedish facilities, as well as chemical analyses and BMP tests of slurry and refuse, the computer-based evaluation tool ORWARE was improved as to accurately describe mass flows through the physical pre-treatment and anaerobic degradation. The environmental and economic performance of the evaluated system was influenced by the TS concentration in the slurry, as well as the distribution of incoming solids between slurry and refuse. The focus to improve the efficiency of these systems should primarily be directed towards minimising the water addition in the pre-treatment provided that this slurry can still be efficiently digested. Second, the amount of refuse should be minimised, while keeping a good quality of the slurry. Electricity use/generation has high impact on GHG emissions and the results of the study are sensitive to assumptions of marginal electricity and of electricity use in the pre-treatment.
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| 6. |
- Ebin, Burcak, 1983, et al.
(författare)
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Investigation of zinc recovery by hydrogen reduction assisted pyrolysis of alkaline and zinc-carbon battery waste
- 2017
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 68, s. 508-517
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Tidskriftsartikel (refereegranskat)abstract
- Zinc (Zn) recovery from alkaline and zinc-carbon (Zn-C) battery waste were studied by a laboratory scale pyrolysis process at a reaction temperature of 950 degrees C for 15-60 min residence time using 5%H-2 (g)-N-2(g) mixture at 1.0 L/min gas flow rate. The effect of different cooling rates on the properties of pyrolysis residue, manganese oxide particles, were also investigated. Morphological and structural characterization of the produced Zn particles were performed. The battery black mass was characterized with respect to the properties and chemical composition of the waste battery particles. The thermodynamics of the pyrolysis process was studied using the HSC Chemistry 5.11 software. A hydrogen, reduction reaction of the battery black mass (washed with Milli-Q water) takes place at the chosen temperature and makes it possible to produce fine Zn particles by rapid condensation following the evaporation of Zn from the pyrolysis batch, The amount of Zn that can be separated from the black mass increases by extending the residence time. Recovery of 99.8% of the Zn was achieved at 950 degrees C for 60 min residence time using 1.0 L/min gas flow rate. The pyrolysis residue contains MnO and Mn2O3 compounds, and the oxidation state of manganese can be controlled by cooling rate and atmosphere. The Zn particles exhibit spherical and hexagonal particle morphology with a particle size varying between 200 nm and 3 mu m. However the particles were formed by aggregation of nanoparticles which are primarily nucleated from the gas phase.
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| 7. |
- Ebin, Burcak, 1983, et al.
(författare)
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Production of zinc and manganese oxide particles by pyrolysis of alkaline and Zn–C battery waste
- 2016
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 51, s. 157-167
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Tidskriftsartikel (refereegranskat)abstract
- Production of zinc and manganese oxide particles from alkaline and zinc–carbon battery black mass was studied by a pyrolysis process at 850–950 °C with various residence times under 1 L/min N2(g) flow rate conditions without using any additive. The particular and chemical properties of the battery waste were characterized to investigate the possible reactions and effects on the properties of the reaction products. The thermodynamics of the pyrolysis process were studied using the HSC Chemistry 5.11 software. The carbothermic reduction reaction of battery black mass takes place and makes it possible to produce fine zinc particles by a rapid condensation, after the evaporation of zinc from a pyrolysis batch. The amount of zinc that can be separated from the black mass is increased by both pyrolysis temperature and residence time. Zinc recovery of 97% was achieved at 950 °C and 1 h residence time using the proposed alkaline battery recycling process. The pyrolysis residue is mainly MnO powder with a low amount of zinc, iron and potassium impurities and has an average particle size of 2.9 μm. The obtained zinc particles have an average particle size of about 860 nm and consist of hexagonal crystals around 110 nm in size. The morphology of the zinc particles changes from a hexagonal shape to s spherical morphology by elevating the pyrolysis temperature.
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| 8. |
- Eboh, Francis Chinweuba, et al.
(författare)
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Economic evaluation of improvements in a waste-to-energy combined heat and power plant
- 2019
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456.
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Tidskriftsartikel (refereegranskat)abstract
- Improving the efficiency of waste-to-energy combined heat and power plants increases their production of both electricity and heat. Economic evaluation of such improvements enables adequate decisions to be made between the various alternatives with respect to economic viability of the plant. In this study, the cost and profitability of different modifications to improve efficiency in a waste-to-energy plant are considered: these include the re-arrangement of air heaters, the introduction of a reheater, flue gas condensation (FGC) and an integrated gasification-combustion process. The base case and the modifications are evaluated and compared when operating either as a combined heat and power plant or as a power plant. Modelling, simulation and cost estimations were performed with the Aspen Plus software. Although the integrated gasification-combustion technology with FGC has the highest exergy efficiency, its higher capital cost is greater than all of the other alternatives. Modification 6, which involves both re-arrangement and changing the air heating medium has the lowest capital cost with respect to enhancing exergy efficiency. Modifications 1 and 7, involving FGC, are the best alternatives for the capital cost per total unit of revenue generated. These modifications not only provides the highest heat production but also the highest net present value (NPV). The base case and the modifications investigated all have positive NPV, indicating that a waste-to-energy combined heat and power plant is an attractive investment. However, an increase of about 122% in the gate fees would be required for a system with only electricity production to be profitable.
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| 9. |
- Edo Gimenez, Mar, et al.
(författare)
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Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF
- 2017
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Ingår i: Waste Management. - Oxford : Elsevier. - 0956-053X .- 1879-2456. ; 68, s. 646-652
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Tidskriftsartikel (refereegranskat)abstract
- Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220°C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.
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| 10. |
- Edo, Mar, et al.
(författare)
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Assessment of chemical and material contamination in waste wood fuels : a case study ranging over nine years
- 2016
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 49, s. 311-319
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Tidskriftsartikel (refereegranskat)abstract
- The increased demand for waste wood (WW) as fuel in Swedish co-combustion facilities during the last years has increased the import of this material. Each country has different laws governing the use of chemicals and therefore the composition of the fuel will likely change when combining WW from different origins. To cope with this, enhanced knowledge is needed on WW composition and the performance of pre-treatment techniques for reduction of its contaminants. In this study, the chemical and physical characteristics of 500 WW samples collected at a co-combustion facility in Sweden between 2004 and 2013 were investigated to determine the variation of contaminant content over time. Multivariate data analysis was used for the interpretation of the data. The concentrations of all the studied contaminants varied widely between sampling occasions, demonstrating the highly variable composition of WW fuels. The efficiency of sieving as a pre-treatment measure to reduce the levels of contaminants was not sufficient, revealing that sieving should be used in combination with other pre-treatment methods. The results from this case study provide knowledge on waste wood composition that may benefit its management. This knowledge can be applied for selection of the most suitable pre-treatments to obtain high quality sustainable WW fuels.
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