1. |
- Arm, Maria
(author)
-
Self-cementing properties of crushed demolished concrete in unbound layers : results from triaxial tests and field tests
- 2001
-
In: Waste Management. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0956-053X .- 1879-2456. ; 21:3, s. 235-239
-
Journal article (peer-reviewed)abstract
- A 2-year study is underway to evaluate the expected growth in stiffness in layers of crushed concrete from demolished structures. This growth is said to be a result of self-cementing properties. The study consists of repeated load triaxial tests on manufactured specimens after different storing time together with falling weight deflectometer, FWD, measurements on test sections. Results so far show a clear increase with time in resilient modulus and in back-calculated layer modulus for all concrete materials. The increase is the largest in the first months and then diminishes. The field measurements show a more considerable growth in stiffness than the laboratory tests, with a doubled value two years after construction. Comparative investigations on natural aggregates, mostly crushed granite do not show any growth in stiffness, neither in the laboratory nor in the field. Consequences for the choice of design modulus are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.
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2. |
- Ecke, Holger
(author)
-
Sequestration of metals in carbonated municipal solid waste incineration (MSWI) fly ash
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 631-640
-
Journal article (peer-reviewed)abstract
- Waste management is in need of a reliable and economical treatment method for metals in fly ashes from municipal solid waste incineration (MSWI). However, no state-of-the-art technique has gained wide acceptance yet. This paper is a synthesis of five elsewhere published investigations covering a project which aimed to assess the possibilities and limitations of adding carbon dioxide (CO2) to fly ash as a stabilization method. Carbonation factors that were studied are the partial pressure of carbon dioxide (CO2), the addition of water, the temperature, and the reaction time. Laboratory experiments were performed applying methods such as factorial experimental design, thermal analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and leaching assays including pHstat titration and sequential extraction. Leaching data were verified and complemented using chemical equilibrium calculations. Data evaluation was performed by means of multivariate statistics such as multiple linear regression, principal component analysis (PCA), and partial least squares (PLS) modeling. It was found that carbonation is a good prospect for a stabilization technique especially with respect to the major pollutants lead (Pb) and zinc (Zn). Their mobility decreased with increasing factor levels. Dominating factors were the partial pressure of CO2 and the reaction time, while temperature and the addition of water were of minor influence. However, the treatment caused a mobilization of cadmium (Cd), requiring further research on possible countermeasures such as metal demobilization through enhanced silicate formation.
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3. |
- Jonsson, Susanne, 1965-, et al.
(author)
-
Transformation of phthalates in young landfill cells
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 641-651
-
Journal article (peer-reviewed)abstract
- Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 ╡g/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions. ⌐ 2003 Elsevier Ltd. All rights reserved.
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4. |
- Kylefors, Katarina, et al.
(author)
-
A comparison of small scale pilot-scale and large-scale tests for predicting leaching behaviour of landfilled wastes
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:1, s. 45-59
-
Journal article (peer-reviewed)abstract
- Landfills generate emissions over long periods, often longer than a lifetime. The longest lasting emission is leachate. In order to estimate the future requirements for leachate treatment, different kinds of leaching tests may be applied. In this paper, shaking leaching tests (SLT), landfill-simulator leaching tests and a field-cell leaching test performed with ash, municipal solid waste (MSW) and MSW+ash are evaluated. The tests are compared and the factors influencing leaching are identified and discussed. The factors are: liquid to solid (L/S) ratio, water withdrawal, recirculation rate, presence or absence of biological processes, size of particles, duration of experiment, temperature and pre-treatment of the waste. The presence of biological processes has the greatest impact on leaching and is the main reason why SLT is less useful for long-term predictions. The landfill simulator tests were found to be useful for several different kinds of predictions. However, they are not reliable for predicting the L/S required for reaching a certain concentration. The possibilities for reliable long-term predictions would be facilitated by a better knowledge of the influence of various factors on leaching. Such an increased knowledge would make it possible to enhance waste stabilisation in leaching tests as well as in full-scale landfills.
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5. |
- Lind, B.B., et al.
(author)
-
Environmental impact of ferrochrome slag in road construction
- 2001
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 21:3, s. 255-264
-
Conference paper (other academic/artistic)abstract
- Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analysed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials. Copyright (C) 2001 Elsevier Science Ltd.Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analyzed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials.
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6. |
- Macsik, Josef, et al.
(author)
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Leachability of V and Cr from LD-Slag/Portland cement stabilised sulphide soil
- 1996
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 16:8, s. 699-709
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Journal article (peer-reviewed)abstract
- The objectives of this study were to improve the mechanical stability of a sulphide soil with additives of an industrial waste product (LD-Slag) and Portland Cement. The criterion of using LD-Slag was if it could be done in an environmentally proper way. Sequential Leaching Tests were performed on monolithic LD-Slag/Portland Cement stabilised sulphide soil samples in order to register the leachability and pollution potentials. Different pH and Eh conditions were established in these tests in order to control the leachability of Na, K, Ca and Mg, which are important during cementation processes inside as well as outside an inforced monolith, and the leachability of V, which is regarded as a pollutant. The contents of Cr and V of pure LD-Slag, monolithic samples and leachates were compared with Canadian and Finnish Maximum Containment Level standards. The investigation showed that acidic conditions will increase the leachability of V. An acidic environment will even change the physical properties of a monolith. However, acidic conditions are not likely to occur in an in-situ anaerobic sulphide soil.
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7. |
- Menad, Nourreddine, et al.
(author)
-
Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:6, s. 483-491
-
Journal article (peer-reviewed)abstract
- Carbothermal treatment tests of electric arc furnace dusts (EAFD) using the Waelz kiln process were carried out in pilot-scale for the production of zinc oxide. The association of halides in the EAFD, and the recycled products, such as zinc oxide fumes and high-grade iron contents fractions were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. XRD reveals the presence of chlorine and fluorine in the dusts in the form of KCl, NaCl and CaF2. An ultra-pure fraction of zinc was obtained after the Double Leaching Waelz Oxide (DLWO) process was performed on the zinc oxide fumes. The halide contents were reduced to approximately 100 ppm Cl and 700 ppm F. The rest of these elements are in the form of CaF2. About 65% F is volatilised as lead and zinc fluorides, 15% is expected in the magnetic fractions and 20% in non-magnetic fractions as CaF2 and MnF2, respectively.
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8. |
- Shen, Huiting, et al.
(author)
-
An overview of recovery of metals from slags
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:10, s. 933-949
-
Journal article (peer-reviewed)abstract
- Various slags are produced as by-products in metallurgical processes or as residues in incineration processes. According to the origins and the characteristics, the main slags can be classified into three categories, namely ferrous slag, non-ferrous slag and incineration slag. This paper analysed and summarised the generation, characteristics and application of various slags, and discussed the potential effects of the slags on the environment. On this basis, a review of a number of methods for recovery of metals from the slags was made. It can be seen that a large amount of slags is produced each year. They usually contain a quantity of valuable metals except for blast furnace slag and they are actually a secondary resource of metals. By applying mineral processing technologies, such as crushing, grinding, magnetic separation, eddy current separation, flotation and so on, leaching or roasting, it is possible to recover metals such as Fe, Cr, Cu, Al, Pb, Zn, Co, Ni, Nb, Ta, Au, and Ag etc. from the slags. Recovery of metals from the slags and utilisation of the slags are important not only for saving metal resources, but also for protecting the environment.
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9. |
- Singh, Maneesh, et al.
(author)
-
Preparation of special cements from red mud
- 1996
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 16:8, s. 665-670
-
Journal article (peer-reviewed)abstract
- Red mud from HINDALCO (Hindustan Aluminium Corporation) Industries Limited, Renukoot, India, contains significant quantities of alumina, iron oxide and silica. Presence of the said constituents makes it a suitable ingredient for the preparation of special cements. Preparation of three varieties of cements was investigated, namely: (a) aluminoferrite (C4AF)- belite (β-C2S) using lime + red mud + fly ash; (b) aluminoferrite-ferrite (C2F)-aluminates (C3A and C12A7) utilising lime + red mud + bauxite; and (c) sulfoaluminate (C4A3S̄)-aluminoferrite-ferrite using lime + red mud + bauxite + gypsum. The effects of composition (proportions of lime, red mud, fly ash, bauxite and gypsum), firing temperature and duration on the properties of cements produced were studied in detail. Cements made from lime + red mud + bauxite or lime + red mud + bauxite + gypsum exhibit strengths comparable or superior to ordinary Portland cement (OPC). On the other hand, those prepared using lime + red mud + fly ash did not have sufficient strength. Moreover, it was not possible to replace bauxite by fly ash (as a source of alumina) in any significant quantity.
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10. |
- Todorovic, Jelena, et al.
(author)
-
Solidification with water as a treatment method for air pollution control residues
- 2003
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 621-629
-
Journal article (peer-reviewed)abstract
- The process of solidification with water was studied on air pollution control (APC) residues from incineration of refuse-derived fuel (RDF) regarding mechanical strength and leaching behaviour of solidified material. Factorial design in two levels was applied to investigate the impact of water addition, time, and temperature to mechanical strength of solidified material. Factors time and temperature, as well as the interaction between the addition of water and time significantly (α=0.05) influenced the mechanical strength of solidified material. The diffusion-leaching test NEN 7345 was performed to investigate if the leaching behaviour of elements from solidified material was determined by diffusion. Since it was found that leaching is not diffusion controlled, the long-term leaching behaviour was not assessed. However, the investigation showed that some of the studied components (Al, Hg, Mn, Pb, Si, and Zn) could be considerably demobilised by solidification with water. Concentrations of As, Cd, Co, Cu, Fe, and Ni were either below or not quite above the detection limits to be included in the analysis of leaching behaviour. The elements least demobilised by solidification were Cl, Cr, K, and Na.
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11. |
- Yan, J. Y., et al.
(author)
-
The long-term acid neutralizing capacity of steel slag
- 2000
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 20:03-feb, s. 217-223
-
Journal article (peer-reviewed)abstract
- The long-term acid neutralizing capacity (ANC) of the electric are furnace slag investigated by batch pH titration, and the neutralizing processes of the slag were evaluated by reaction path modeling. Reaction time plays an important role for the determination of the ANC for the steel slag. The relatively slow reactions may give large contributions to the ANC for a long-term leaching process, pH-dependent reactivities of the steel slag were found in the high pH range. The neutralizing rates at high pH were much slower than that at relatively low pH. Below pH 9, the reaction rates became less pH-dependent and usually fast. The features of neutralizing reactions of the slag may be explained by its mineralogical composition and dissolution kinetics in the neutralizing processes.
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12. |
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13. |
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14. |
- Aljaradin, Mohammad, et al.
(author)
-
Current situation of municipal solid waste landfills in Jordan
- 2011
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 31:8, s. 1897-1898
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Journal article (pop. science, debate, etc.)abstract
- Jordan has seen a large increase in inhabitants over the past five decades as a result of a high population growth rate and forced migrations. Economic and cultural development has improved the standard of living and changed consumer habits, resulting in an increase in the volume of municipal solid waste (MSW) over time. The rate of production of MSW has been estimated at about 1,964,284 ton annually with an average generation rate of 0.95 kg/ cap/day in urban and 0.85 kg/cap/day in rural areas (SWEEP, 2010) and is expected to reach 2.5 million ton by 2015. The major fraction of MSW composition is organic (Fig. 1), which implies a high moisture content value, as expected in a developing country where food is the major component of the solid waste stream (Abu Qdais, 2007). About 86% of the MSW is decomposable and recyclable, while the remainder is inert matter. The solid waste volume is still increasing at high rates due to the rapid population increase as well as the change in living standards and consumption patterns.
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15. |
- Alvarez, Rene, et al.
(author)
-
Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano
- 2008
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 28:10, s. 1933-1940
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Journal article (peer-reviewed)abstract
- Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure front llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-1 reactors at a temperature of 25 degrees C with 30 days of hydraulic retention time (HRT) and ail organic loading rate (OLR) of 1.8 kg VS m(-3) d(-1). Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process. (C) 2007 Elsevier Ltd. All rights reserved.
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16. |
- Amjad, Um-e-Salma, et al.
(author)
-
Catalytic cracking of polystyrene pyrolysis oil: Effect of Nb2O5 and NiO/Nb2O5 catalyst on the liquid product composition
- 2022
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 141, s. 240-250
-
Journal article (peer-reviewed)abstract
- The catalytic cracking of polystyrene pyrolysis oil was investigated over a Nb2O5 and a NiO/Nb2O5 catalyst in a fixed bed reactor. First, the pyrolysis of two different polystyrene feedstock (polystyrene foam and polystyrene pellet) was carried out in a semi-batch reactor, and the resulting polystyrene pellets pyrolysis oil was selected for catalytic cracking reaction because of its high liquid yield (85%). Catalytic cracking experiments were then performed at different temperatures (350–500 °C) using Nb2O5 or NiO/Nb2O5 catalyst. Gas chromatography–mass spectrometry analysis of liquid product obtained from the catalytic cracking process showed that the dimers in the pyrolysis oil were converted to monomers during the catalytic cracking process. The catalytic cracking results also showed that the NiO/Nb2O5 catalyst (having slightly higher acidic sites) had slightly higher activity for monomer conversion than the Nb2O5 catalyst (having less acidic sites). X-ray diffraction, transmission electron microscopy, pyridine Fourier transform infrared spectroscopy, NH3 Temperature Programmed Desorption and X-ray photoelectron spectroscopy were used to characterize the catalyst. The highest catalytic cracking activity was observed at 400 °C with the Nb2O5 catalyst with 4% toluene, 6% ethylbenzene, approximately 50% styrene, 13% α-methyl styrene, and only 6% of dimers in the liquid oil. The increase in temperature positively affected the yield of gases during catalytic cracking process.
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17. |
- Andersson, Camilla, et al.
(author)
-
Direct and indirect effects of waste management policies on household waste behaviour : The case of Sweden
- 2018
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 76, s. 19-27
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Journal article (peer-reviewed)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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18. |
- Andersson, Magnus, 1983, et al.
(author)
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Are scarce metals in cars functionally recycled?
- 2017
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 60, s. 407-416
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Journal article (peer-reviewed)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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19. |
- Andersson, S., et al.
(author)
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Sulfur recirculation for increased electricity production in Waste-to-Energy plants
- 2014
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 34:1, s. 67-78
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Journal article (peer-reviewed)abstract
- Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Goteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop. The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO3 concentrations, which may otherwise induce low temperature corrosion. In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450 degrees C and 525 degrees C) compared to the reference exposure. The corrosion rates were reduced by 60-90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525 degrees C with sulfur recirculation in operation were similar or lower compared to those measured at 450 degrees C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion.
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20. |
- André, Hampus, 1989, et al.
(author)
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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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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 88, s. 268-279
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Journal article (peer-reviewed)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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21. |
- Andreas, Lale, et al.
(author)
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Steel slags in a landfill top cover : Experiences from a full-scale experiment
- 2014
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 34:3, s. 692-701
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Journal article (peer-reviewed)abstract
- A full scale field study has been carried out in order to test and evaluate the use of slags from high-alloy steel production as the construction materials for a final cover of an old municipal landfill. Five test areas were built using different slag mixtures within the barrier layer (liner). The cover consisted of a foundation layer, a liner with a thickness of 0.7 m, a drainage layer of 0.3 m, a protection layer of 1.5 m and a vegetation layer of 0.25 m. The infiltration varied depending on the cover design used, mainly the liner recipe but also over time and was related to seasons and precipitation intensity. The test areas with liners composed of 50% electric arc furnace (EAF) slag and 50% cementitious ladle slag (LS) on a weight basis and with a proper consistence of the protection layer were found to meet the Swedish infiltration criteria of ⩽50 l (m2 a)−1 for final covers for landfills for non-hazardous waste: the cumulative infiltration rates to date were 44, 19 and 0.4 l (m2 a)−1 for A1, A4 and A5, respectively. Compared to the precipitation, the portion of leachate was always lower after the summer despite high precipitation from June to August. The main reason for this is evapotranspiration but also the fact that the time delay in the leachate formation following a precipitation event has a stronger effect during the shorter summer sampling periods than the long winter periods. Conventional techniques and equipment can be used but close cooperation between all involved partners is crucial in order to achieve the required performance of the cover. This includes planning, method and equipment testing and quality assurance.
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22. |
- Andreasi Bassi, Susanna, et al.
(author)
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A life cycle assessment framework for large-scale changes in material circularity
- 2021
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 135, s. 360-371
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Journal article (peer-reviewed)abstract
- Increasing material circularity is high on the agenda of the European Union in order to decouple environmental impacts and economic growth. While life cycle assessment (LCA) is useful for quantifying the associated environmental impacts, consistent LCA modeling of the large-scale changes arising from policy targets addressing material circularity (i.e., recycled content and recycling rate) is challenging. In response to this, we propose an assessment framework addressing key steps in LCA, namely, goal definition, functional unit, baseline versus alternative scenario definition, and modeling of system responses. Regulatory and economic aspects (e.g., trends in consumption patterns, market responses, market saturation, and legislative side-policies affecting waste management) are emphasized as critical for the identification of potential system responses and for supporting regulatory interventions required to reach the intended environmental benefits. The framework is recommended for LCA studies focusing on system-wide consequences where allocation between product life cycles is not relevant; however, the framework can be adapted to include allocation. The application of the framework was illustrated by an example of implementing a policy target for 2025 of 70% recycled content in PET trays in EU27+1. It was demonstrated that neglecting large-scale market responses and saturation lead to an overestimation of the environmental benefits from the policy target and that supplementary initiatives are required to achieve the full benefits at system level.
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23. |
- Arm, Maria, et al.
(author)
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Technical environmental long-term properties of industrial residues : summary of field and laboratory investigations
- 2011
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 31:1, s. 101-107
-
Journal article (peer-reviewed)abstract
- In Sweden, use of industrial residues is still hindered by concern for their long-term properties. A three-year research project was therefore initiated aiming to (1) identify the crucial processes of ageing related to the usefulness of residues in roads; (2) investigate the consequences of these processes for technical and environmental properties of the residues, and (3) propose a method for accelerated ageing to predict the long-term properties. This paper gives an overview of the project methodology, a summary of the test results and references to papers where further details are given. The project, running through 2006-2008, compared naturally aged samples of two residues used as sub-bases in existing asphalt paved roads with samples of fresh residues from producers' piles. Steel slag of electric arc furnace (EAF) type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterised in order to identify which ageing processes had been crucial. The results showed that: - Bottom ash from the pavement edge was more aged than bottom ash from the road centre. However, no difference in pH was found, instead the differences were caused by differences in water exposure. - Steel slag from the pavement edge showed traces of carbonation and leaching processes, whereas slag from the road centre was identical to fresh slag. - Water exposure to the subbase materials after ten years in an asphalt paved road was calculated to less than 0.1–0.5 litres per kg. - Ageing reactions in steel slag and MSWI bottom ash, ready for use, were too small to be verified by laboratory measurement of deformation properties under loaded conditions. An accelerated ageing test for steel slag was set up to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material. An accelerated ageing test for bottom ash was set up to achieve the pozzolan reactions that were observed in SEM analyses of in situ specimens. It is recommended to use uncrushed particles when properties of aged material are studied, in order to preserve the original particle surfaces.
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24. |
- Bagheri, Marzieh, et al.
(author)
-
Introducing hydrothermal carbonization to sewage sludge treatment systems—a way of improving energy recovery and economic performance?
- 2023
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 170, s. 131-143
-
Journal article (peer-reviewed)abstract
- Hydrothermal carbonization (HTC) can mitigate the disposal costs of sewage sludge in a wastewater treatment plant. This study analyzes the impact of integrating HTC with anaerobic digestion (AD) and combustion from a combined energy and economic performance perspective. Net energy balance and investment opportunity are investigated for a number of technical scenarios considering i) different combinations of the technologies: AD + HTC, AD + thermal dryer + combustion, and AD + HTC + combustion, ii) different options for HTC process water treatment: wet oxidation (WO) + AD, and direct return to AD, and iii) different products: heat-only, heat and electricity, hydrochar, and phosphorus.The results show trade-offs between investment cost, self-supplement of heat, and output electricity when WO is used. In AD + HTC, net heat output decreases compared to the reference plant, but avoided disposal costs and hydrochar revenue result in profitable investment when the process water is directly returned to the AD. Although HTC has a lower heat demand than the thermal dryer, replacing the thermal dryer with HTC is only possible when AD, HTC, and combustion are connected, or when WO covers HTC’s heat demand. HTC may impair the electricity production because of the necessity for a high-temperature heat source, whereas the thermal dryer can utilize a low-temperature heat source. In conclusion, energy advantages of HTC in AD + HTC + combustion are insufficient to provide a promising investment opportunity due to high investment costs of HTC. The investment opportunity improves by co-combustion of hydrochar and external sludge.
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25. |
- Barbato, Paula Martina, et al.
(author)
-
Quality degradation in glass recycling: substitutability model proposal
- 2024
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 182, s. 124-131
-
Journal article (peer-reviewed)abstract
- The sustainability assessment of waste management systems requires tools capable of evaluating material quality degradation during recycling. Existing research has predominantly focused on the development of substitutability models for plastics, leaving a gap in addressing other materials like glass. Glass is commonly regarded as endlessly recyclable, even though its actual recyclability depends on several crucial factors, such as colour and pollutant contamination. Many Life Cycle Assessment (LCA) studies in this field assume a one-to-one substitution coefficient, neglecting material deterioration and inaccurately representing real-world scenarios. This study proposes and assesses a substitutability model for glass, aiming to measure the replacement extent between virgin materials and recycled crushed glass (cullet). The methodology is based on two key factors: technical quality substitutability, considering impurities and colour contaminations in cullet, and market applicability, accounting for market demand. Once formulated, the model was applied to a European case study on glass waste treatment. Two scenarios were considered: one assuming complete substitution between cullet and raw materials, the other incorporating quality degradation. Findings indicate that, accounting for quality degradation, only 83% of cullet effectively replaces raw materials, resulting in a decrease of the benefit associated with recycling of 13–23% for the different examined impact categories, compared to complete replacement assumption. This underscores the importance of considering quality deterioration in glass recycling impact assessments.
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26. |
- Behjat, Marta, 1991, et al.
(author)
-
Environmental assessment of phosphorus recovery from dairy sludge: A comparative LCA study
- 2024
-
In: Waste Management. - 0956-053X .- 1879-2456. ; 187, s. 50-60
-
Journal article (peer-reviewed)abstract
- Phosphate rock is a finite, non-renewable mineral resource that is used primarily in fertiliser production. The scarcity and the increasing demand for this finite material led the European Commission to include it in the critical raw material list in 2014. As a consequence, efforts have been directed towards enhancing material use efficiency, initiating recycling efforts, and formulating waste policies to mitigate the criticality of raw materials. Interest in the development of technologies for nutrient recovery from organic waste streams has increased in recent years, and dairy processing sludge (DPS) is a potential input waste stream. Although the recovery of P from DPS can contribute to more circular flows of nutrients in society, it has to be assessed whether there are also overall environmental gains. This paper reports on a life cycle assessment (LCA) of the environmental impacts of three scenarios for phosphorus (P) recovery involving hydrothermal carbonization (HTC) and struvite precipitation and a comparison to a reference drying scenario. HTC produces a solid fraction (hydrochar), and a liquid fraction (process water) and in one of the scenarios (Scenario 3), leaching the hydrochar for additional P recovery is considered. From the process water as well as from the hydrochar leachate, P is precipitated in the form of struvite. Scenarios 1 and 2 both consider HTC and struvite production with the only difference that the hydrochar is used as a fuel instead of as a fertilizer in the latter case, and Scenario 3 adds leaching of the hydrochar with subsequent struvite production and considers that hydrochar is used as a fuel. In the fourth (reference) scenario, dewatering and drying of DPS is considered. The recovered product use in agriculture was not assessed at this stage. The assessment of the emerging technologies in Scenarios 1–3 was done by studying the technologies in early stages of development but modelling them as more developed in the future. Additional functions beyond the functional unit of one kg of P recovered were handled through a system expansion by substitution approach. This way, the system was credited for calcium ammonium nitrate (CAN) production in all scenarios and for wood chips production in Scenarios 2 and 3. Looking at net outcomes for all scenarios, the life cycle impact indicator results for scenario 2 are lower than the other scenarios in several impact categories. Large gains in scenario 2 are related to the avoided production of wood chips.
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27. |
- Benavente, Veronica, et al.
(author)
-
Co-hydrothermal carbonization of microalgae and digested sewage sludge : Assessing the impact of mixing ratios on the composition of primary and secondary char
- 2024
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 174, s. 429-438
-
Journal article (peer-reviewed)abstract
- The role of microalgae cultivation in wastewater treatment and reclamation has been studied extensively, as has the potential utility of the resulting algal biomass. Most methods for processing such biomass generate solid residues that must be properly managed to comply with current sustainable resource utilization requirements. Hydrothermal carbonization (HTC) can be used to process both individual wet feedstocks and mixed feedstocks (i.e., co-HTC). Here, we investigate co-HTC using microalgae and digested sewage sludge as feedstocks. The objectives were to (i) study the material's partitioning into solid and liquid products, and (ii) characterize the products’ physicochemical properties. Co-HTC experiments were conducted at 180–250°C using mixed microalgae/sewage sludge feedstocks with the proportion of sewage sludge ranging from 0 to 100 %. Analyses of the hydrochar composition and the formation and composition of secondary char revealed that the content of carbonized material in the product decreased as the proportion of sewage sludge in the feedstock increased under fixed carbonization conditions. The properties of the hydrochars and the partitioning of material between the liquid phase and the hydrochar correlated linearly with the proportion of microalgae in mixed feedstocks, indicating that adding sewage sludge to microalgae had weak or non-existent synergistic effects on co-HTC outcomes. However, the proportion of sewage sludge in the feedstock did affect the secondary char. For example, adding sewage sludge reduced the abundance of carboxylic acids and ketones as well as the concentrations of higher molecular weight cholesterols. Such changes may alter the viable applications of the hydrochar.
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28. |
- Bernstad, Anna, et al.
(author)
-
A life cycle approach to the management of household food waste - A Swedish full-scale case study.
- 2011
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 31, s. 1879-1896
-
Journal article (peer-reviewed)abstract
- Environmental impacts from incineration, decentralised composting and centralised anaerobic digestion of solid organic household waste are compared using the EASEWASTE LCA-tool. The comparison is based on a full scale case study in southern Sweden and used input-data related to aspects such as source-separation behaviour, transport distances, etc. are site-specific. Results show that biological treatment methods - both anaerobic and aerobic, result in net avoidance of GHG-emissions, but give a larger contribution both to nutrient enrichment and acidification when compared to incineration. Results are to a high degree dependent on energy substitution and emissions during biological processes. It was seen that if it is assumed that produced biogas substitute electricity based on Danish coal power, this is preferable before use of biogas as car fuel. Use of biogas for Danish electricity substitution was also determined to be more beneficial compared to incineration of organic household waste. This is a result mainly of the use of plastic bags in the incineration alternative (compared to paper bags in the anaerobic) and the use of biofertiliser (digestate) from anaerobic treatment as substitution of chemical fertilisers used in an incineration alternative. Net impact related to GWP from the management chain varies from a contribution of 2.6kg CO(2)-eq/household and year if incineration is utilised, to an avoidance of 5.6kg CO(2)-eq/household and year if choosing anaerobic digestion and using produced biogas as car fuel. Impacts are often dependent on processes allocated far from the control of local decision-makers, indicating the importance of a holistic approach and extended collaboration between agents in the waste management chain.
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29. |
- Bernstad, Anna
(author)
-
Household food waste separation behavior and the importance of convenience.
- 2014
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 34:7, s. 1317-1323
-
Journal article (peer-reviewed)abstract
- Two different strategies aiming at increasing household source-separation of food waste were assessed through a case-study in a Swedish residential area (a) use of written information, distributed as leaflets amongst households and (b) installation of equipment for source-segregation of waste with the aim of increasing convenience food waste sorting in kitchens. Weightings of separately collected food waste before and after distribution of written information suggest that this resulted in neither a significant increased amount of separately collected food waste, nor an increased source-separation ratio. After installation of sorting equipment in households, both the amount of separately collected food waste as well as the source-separation ratio increased vastly. Long-term monitoring shows that results where longstanding. Results emphasize the importance of convenience and existence of infrastructure necessary for source-segregation of waste as important factors for household waste recycling, but also highlight the need of addressing these aspects where waste is generated, i.e. already inside the household.
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30. |
- Bernstad, Anna, et al.
(author)
-
Need for improvements in physical pretreatment of source-separated household food waste.
- 2013
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 33:3, s. 746-754
-
Journal article (peer-reviewed)abstract
- The aim of the present study was to investigate the efficiency in physical pretreatment processes of source-separated solid organic household waste. The investigation of seventeen Swedish full-scale pretreatment facilities, currently receiving separately collected food waste from household for subsequent anaerobic digestion, shows that problems with the quality of produced biomass and high maintenance costs are common. Four full-scale physical pretreatment plants, three using screwpress technology and one using dispergation technology, were compared in relation to resource efficiency, losses of nitrogen and potential methane production from biodegradable matter as well as the ratio of unwanted materials in produced biomass intended for wet anaerobic digestion. Refuse generated in the processes represent 13-39% of TS in incoming wet waste. The methane yield from these fractions corresponds to 14-36Nm(3)/ton separately collected solid organic household waste. Also, 13-32% of N-tot in incoming food waste is found in refuse. Losses of both biodegradable material and nutrients were larger in the three facilities using screwpress technology compared to the facility using dispersion technology.(1) Thus, there are large potentials for increase of both the methane yield and nutrient recovery from separately collected solid organic household waste through increased efficiency in facilities for physical pretreatment. Improved pretreatment processes could thereby increase the overall environmental benefits from anaerobic digestion as a treatment alternative for solid organic household waste.
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31. |
- Bernstad, Anna, et al.
(author)
-
Property-close source separation of hazardous waste and waste electrical and electronic equipment - A Swedish case study.
- 2011
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 31, s. 536-543
-
Journal article (peer-reviewed)abstract
- Through an agreement with EEE producers, Swedish municipalities are responsible for collection of hazardous waste and waste electrical and electronic equipment (WEEE). In most Swedish municipalities, collection of these waste fractions is concentrated to waste recycling centres where households can source-separate and deposit hazardous waste and WEEE free of charge. However, the centres are often located on the outskirts of city centres and cars are needed in order to use the facilities in most cases. A full-scale experiment was performed in a residential area in southern Sweden to evaluate effects of a system for property-close source separation of hazardous waste and WEEE. After the system was introduced, results show a clear reduction in the amount of hazardous waste and WEEE disposed of incorrectly amongst residual waste or dry recyclables. The systems resulted in a source separation ratio of 70wt% for hazardous waste and 76wt% in the case of WEEE. Results show that households in the study area were willing to increase source separation of hazardous waste and WEEE when accessibility was improved and that this and similar collection systems can play an important role in building up increasingly sustainable solid waste management systems.
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32. |
- Bernstad, Anna, et al.
(author)
-
Review of comparative LCAs of food waste management systems - Current status and potential improvements.
- 2012
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456.
-
Journal article (peer-reviewed)abstract
- Twenty-five comparative cycle assessments (LCAs) addressing food waste treatment were reviewed, including the treatment alternatives landfill, thermal treatment, compost (small and large scale) and anaerobic digestion. The global warming potential related to these treatment alternatives varies largely amongst the studies. Large differences in relation to setting of system boundaries, methodological choices and variations in used input data were seen between the studies. Also, a number of internal contradictions were identified, many times resulting in biased comparisons between alternatives. Thus, noticed differences in global warming potential are not found to be a result of actual differences in the environmental impacts from studied systems, but rather to differences in the performance of the study. A number of key issues with high impact on the overall global warming potential from different treatment alternatives for food waste were identified through the use of one-way sensitivity analyses in relation to a previously performed LCA of food waste management. Assumptions related to characteristics in treated waste, losses and emissions of carbon, nutrients and other compounds during the collection, storage and pretreatment, potential energy recovery through combustion, emissions from composting, emissions from storage and land use of bio-fertilizers and chemical fertilizers and eco-profiles of substituted goods were all identified as highly relevant for the outcomes of this type of comparisons. As the use of LCA in this area is likely to increase in coming years, it is highly relevant to establish more detailed guidelines within this field in order to increase both the general quality in assessments as well as the potentials for cross-study comparisons.
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33. |
- Bernstad, Anna, et al.
(author)
-
Separate collection of household food waste for anaerobic degradation - Comparison of different techniques from a systems perspective.
- 2012
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 32:5, s. 806-815
-
Journal article (peer-reviewed)abstract
- Four systems for household food waste collection are compared in relation the environmental impact categories eutrophication potential, acidification potential, global warming potential as well as energy use. Also, a hotspot analysis is performed in order to suggest improvements in each of the compared collection systems. Separate collection of household food waste in paper bags (with and without drying prior to collection) with use of kitchen grinders and with use of vacuum system in kitchen sinks were compared. In all cases, food waste was used for anaerobic digestion with energy and nutrient recovery in all cases. Compared systems all resulted in net avoidance of assessed environmental impact categories; eutrophication potential (-0.1 to -2.4kg NO(3)(-)eq/ton food waste), acidification potential (-0.4 to -1.0kg SO(2)(-)eq/ton food waste), global warming potential (-790 to -960kg CO(2)(-)eq/ton food waste) and primary energy use (-1.7 to -3.6GJ/ton food waste). Collection with vacuum system results in the largest net avoidence of primary energy use, while disposal of food waste in paper bags for decentralized drying before collection result in a larger net avoidence of global warming, eutrophication and acidification. However, both these systems not have been taken into use in large scale systems yet and further investigations are needed in order to confirm the outcomes from the comparison. Ranking of scenarios differ largely if considering only emissions in the foreground system, indicating the importance of taking also downstream emissions into consideration when comparing different collection systems. The hot spot identification shows that losses of organic matter in mechanical pretreatment as well as tank connected food waste disposal systems and energy in drying and vacuum systems reply to the largest impact on the results in each system respectively.
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34. |
- Bernstad, Anna, et al.
(author)
-
Tank-connected food waste disposer systems - Current status and potential improvements.
- 2012
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 33:1, s. 193-203
-
Journal article (peer-reviewed)abstract
- An unconventional system for separate collection of food waste was investigated through evaluation of three full-scale systems in the city of Malmö, Sweden. Ground food waste is led to a separate settling tank where food waste sludge is collected regularly with a tank-vehicle. These tank-connected systems can be seen as a promising method for separate collection of food waste from both households and restaurants. Ground food waste collected from these systems is rich in fat and has a high methane potential when compared to food waste collected in conventional bag systems. The content of heavy metals is low. The concentrations of N-tot and P-tot in sludge collected from sedimentation tanks were on average 46.2 and 3.9g/kg TS, equalling an estimated 0.48 and 0.05kgN-tot and P-tot respectively per year and household connected to the food waste disposer system. Detergents in low concentrations can result in increased degradation rates and biogas production, while higher concentrations can result in temporary inhibition of methane production. Concentrations of COD and fat in effluent from full-scale tanks reached an average of 1068mg/l and 149mg/l respectively over the five month long evaluation period. Hydrolysis of the ground material is initiated between sludge collection occasions (30days). Older food waste sludge increases the degradation rate and the risks of fugitive emissions of methane from tanks between collection occasions. Increased particle size decreases hydrolysis rate and could thus decrease losses of carbon and nutrients in the sewerage system, but further studies in full-scale systems are needed to confirm this.
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35. |
- Bernstad Saraiva, Anna, et al.
(author)
-
Lifecycle assessment of a system for food waste disposers to tank : A full-scale system evaluation
- 2016
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 54, s. 169-177
-
Journal article (peer-reviewed)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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36. |
- Biganzoli, Laura, et al.
(author)
-
Aluminium recovery vs. hydrogen production as resource recovery options for fine MSWI bottom ash fraction
- 2013
-
In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 33:5, s. 1174-1181
-
Journal article (peer-reviewed)abstract
- Waste incineration bottom ash fine fraction contains a significant amount of aluminium, but previous works have shown that current recovery options based on standard on-step Eddy Current Separation (ECS) have limited efficiency. In this paper, we evaluated the improvement in the efficiency of ECS by using an additional step of crushing and sieving. The efficiency of metallic Al recovery was quantified by measuring hydrogen gas production. The ash samples were also tested for total aluminium content with X-ray fluorescence spectroscopy (XRF). As an alternative to material recovery, we also investigated the possibility to convert residual metallic Al into useful energy, promoting H-2 gas production by reacting metallic Al with water at high pH. The results show that the total aluminium concentration in the <4 mm bottom ash fraction is on average 8% of the weight of the dry ash, with less than 15% of it being present in the metallic form. Of this latter, only 21% can be potentially recovered with ECS combined with crushing and sieving stages and subsequently recycled. For hydrogen production, using 10 M NaOH at 1 L/S ratio results in the release of 6-111 of H-2 gas for each kilogram of fine dry ash, equivalent to an energy potential of 118 kJ. (C) 2013 Elsevier Ltd. All rights reserved.
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37. |
- Björklund, Anna, et al.
(author)
-
Life cycle assessment of a national policy proposal - The case of a Swedish waste incineration tax
- 2007
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 27:8, s. 1046-1058
-
Journal article (peer-reviewed)abstract
- At the core of EU and Swedish waste policy is the so-called waste hierarchy, according to which waste should first be prevented, but should otherwise be treated in the following order of prioritisation: reuse, recycling when environmentally motivated, energy recovery, and last landfilling. Some recent policy decisions in Sweden aim to influence waste management in the direction of the waste hierarchy. In 2001 a governmental commission assessed the economic and environmental impacts of introducing a weight-based tax on waste incineration, the purpose of which would be to encourage waste reduction and increase materials recycling and biological treatments This paper presents the results of a life cycle assessment (LCA) of the waste incineration tax proposal. It was done in the context of a larger research project concerning the development and testing of a framework for Strategic Environmental Assessment (SEA). The aim of this paper is to assess the life cycle environmental impacts of the waste incineration tax proposal, and to investigate whether there are any possibilities of more optimal design of such a tax. The proposed design of the waste incineration tax results in increased recycling, but only in small environmental improvements. A more elaborate tax design is suggested, in which the tax level would partly be related to the fossil carbon content of the waste.
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38. |
- Brancoli, Pedro, 1989-, et al.
(author)
-
Environmental impacts of waste management and valorisation pathways for surplus bread in Sweden
- 2020
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 117, s. 136-145
-
Journal article (peer-reviewed)abstract
- Bread waste represents a significant part of food waste in Sweden. At the same time, the return system established between bakeries and retailers enables a flow of bread waste that is not contaminated with other food waste products. This provides an opportunity for alternative valorisation and waste management options, in addition to the most common municipal waste treatment, namely anaerobic digestion and incineration. An attributional life cycle assessment of the management of 1 kg of surplus bread was conducted to assess the relative environmental impacts of alternative and existing waste management options. Eighteen impact categories were assessed using the ReCiPe methodology. The different management options that were investigated for the surplus bread are donation, use as animal feed, beer production, ethanol production, anaerobic digestion, and incineration. These results are also compared to reducing the production of bread by the amount of surplus bread (reduction at the source). The results support a waste hierarchy where reduction at the source has the highest environmental savings, followed by use of surplus bread as animal feed, donation, for beer production and for ethanol production. Anaerobic digestion and incineration offer the lowest environmental savings, particularly in a low-impact energy system. The results suggests that Sweden can make use of the established return system to implement environmentally preferred options for the management of surplus bread.
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39. |
- Carlos-Pinedo, Sandra, et al.
(author)
-
Assessment of a full-scale solid-state anaerobic co-digestion: A multi-component substrate analysis by using ORWARE
- 2022
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 146, s. 36-43
-
Journal article (peer-reviewed)abstract
- Long-term sustainable biogas production requires different raw material alternatives, especially when reducing the most desirable organic substrate, food waste, which has been set as a goal in the 2030 Agenda. In Sweden, horse manure (HM) is generated in large quantities, and due to its physical and chemical characteristics, it has the potential to be used as a raw material to produce biogas through anaerobic digestion (AD). In order to investigate the challenges that HM digestion can impose in terms of methane yield and/or digestate quality, the modified ORganic WAste REsearch (ORWARE) AD model was applied. The aim was to study the effects of different substrates and combinations of these on the AD process during a full-scale solid-state (SS)-AD. In this sense, the model allows for the analysis of the digestion process of multicomponent substrates at the element level. The simulation results suggested that the replacement of green waste (GW) by HM with wood chips as bedding material gave the best improvement in terms of energy turnover; the liquid fraction of the digestate of this mixture of substrates presented the highest concentration in all the nutrients analyzed, specifically in total carbon-biological and phosphorus. The nutrient concentrations in the digestate from the aforementioned scenario are in line with the SPCR120 certification.
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40. |
- Carlos-Pinedo, Sandra, et al.
(author)
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Study of the digestion process at a full-scale solid-state biogas plant by using ORWARE : Model modification and implementation
- 2020
-
In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 107, s. 133-142
-
Journal article (peer-reviewed)abstract
- The configuration of the reactor influences the digestion process and thus the product yields; other factors such as the rate of biogas production or biogas loss also affect the process specifically with high solid configuration. With these in mind, the ORganic WAste REsearch (ORWARE) anaerobic digestion sub-model was modified to be able to study solid-state anaerobic digestion (SS-AD) (using plug-flow reactor). The simulation results from the updated model agreed with the operational data with respect to methane yield, digestate yield and energy turnover. The model was found to be sensitive to changes in feedstock composition but to a lesser extent to changes in process temperature and retention time. By applying the model on several cases of liquid anaerobic digestion (L-AD), it was noticed that L-AD at mesophilic condition with 25 retention days seemed to be superior to other cases of L-AD with regard to energy turnover. However, even if similar methane production were observed for L-AD and SS-AD, the model suggested higher energy turnover for the case of SS-AD at thermophilic condition, being 10% more in average in comparison with cases of L-AD.
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41. |
- Carlsson, My, et al.
(author)
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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
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 38, s. 117-125
-
Journal article (peer-reviewed)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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42. |
- Carlsson, My, et al.
(author)
-
The effects of substrate pre-treatment on anaerobic digestion systems : a review
- 2012
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 32:9, s. 1634-1650
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Journal article (peer-reviewed)abstract
- Focus is placed on substrate pre-treatment in anaerobic digestion (AD) as a means of increasing biogas yields using today’s diversified substrate sources. Current pre-treatment methods to improve AD are being examined with regard to their effects on different substrate types, highlighting approaches and associated challenges in evaluating substrate pre-treatment in AD systems and its influence on the overall system of evaluation. WWTP residues represent the substrate type that is most frequently assessed in pre-treatment studies, followed by energy crops/harvesting residues, organic fraction of municipal solid waste, organic waste from food industry and manure. The pre-treatment effects are complex and generally linked to substrate characteristics and pre-treatment mechanisms. Overall, substrates containing lignin or bacterial cells appear to be the most amendable to pre-treatment for enhancing AD. Approaches used to evaluate AD enhancement in different systems is further reviewed and challenges and opportunities for improved evaluations are identified.
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43. |
- Caspersen, Siri, et al.
(author)
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Nutrient challenges with solid-phase anaerobic digestate as a peat substitute-Storage decreased ammonium toxicity but increased phosphorus availability
- 2023
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In: Waste Management. - 0956-053X .- 1879-2456. ; 165, s. 128-139
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Journal article (peer-reviewed)abstract
- The solid fraction (SD) obtained after liquid - solid separation of anaerobic digestate is interesting as a potential fertilizer as well as a peat substitute in horticultural growing substrates. We investigated the effect of incubation of the SD obtained by screw-press separation of digestate produced from food waste and plant residues on potentially plant available mineral nutrients and plant growth. The NH4-N concentration was initially > 1000 mg L-1 but rapidly decreased, probably due to NH3 emission promoted by a high initial pH. No nitrate was detected during the first four weeks of incubation. The concentrations of potentially available P and Mg were closely related and strongly increased during incubation. The effect of adding 20 or 30 vol% of SD to a peat-based growing substrate on the growth of basil and lettuce was investigated before and after the incubation period. With the unincubated SD, the initial substrate NH4-N of 200-300 mg L-1 was potentially phytotoxic. Plant growth response ranged from inhibition to stimulation, probably reflecting variation in substrate ammonium status. After 96 days of incubation, ammonium concentrations had decreased with > 50% and basil growth was generally positively affected by addition of incubated SD. However, available P concentrations of 140-210 mg L-1 in the incubated substrates posed a high risk of P leakage. In conclusion, storage greatly reduced NH4-N con-centrations and phytotoxicity when the SD was used as a partial substituent for peat in a horticultural growing substrate. Measures are needed, however, to limit available P concentrations in high-P solid digestate fractions.
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44. |
- Christensen, T. H., et al.
(author)
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Application of LCA modelling in integrated waste management
- 2020
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In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 118, s. 313-322
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Journal article (peer-reviewed)abstract
- Life cycle assessment (LCA) has been used in waste management for the last two decades and hundreds of journal papers have been published. The use of LCA in waste management has provided a much-improved holistic view of waste management including waste flows and potential environmental impacts. Although much knowledge has been obtained from LCA studies, there is still a need to use LCA models in integrated waste management. This paper describes six areas where LCA is expected to play a role in waste management in the future: 1) understanding an existing waste management system; 2) improving existing waste management systems; 3) comparing alternative technologies/ technology performance; 4) technology development/prospective technologies; 5) policy development/strategic development; and 6) reporting. Illustrative examples are provided for each application area.
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45. |
- Cornelis, Geert, 1978, et al.
(author)
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Antimony leaching from MSWI bottom ash: Modelling of the effect of pH and carbonation
- 2012
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 32:2, s. 278-286
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Journal article (peer-reviewed)abstract
- Development of treatment methods to reduce Sb leaching from municipal solid waste incinerator (MSWI) bottom ash, such as accelerated carbonation, is being complicated by insufficient understanding of Sb geochemistry. The leaching of antimonate (Sb(V)) and antimonite (Sb(III)) in MSWI bottom was studied as a function of pH and degree of carbonation. While total (Sb(V)+Sb(III)) leaching was lowest (1.2mgkg-1) at the natural pH (i.e. 10.6) of uncarbonated bottom ash, HPLC-ICP-MS analysis showed that acidification and carbonation increased Sb(V) leaching, but decreased Sb(III) leaching, probably because Sb(III)(OH)4- became less stable. PHREEQC geochemical modelling suggested that Sb(V) concentrations approached equilibrium with the romeites, i.e. calcium antimonates, Ca1.13Sb2(OH)0.26·0.74H2O at pH=10.6 and Ca[Sb(OH)6]2at pH=8. It is hypothesised that not interaction with ettringite but dissolution of romeite controls antimonate leaching in the pH range 8-11 in MSWI bottom ash, because while Ca is preferentially leached from romeite, the mineral structures containing more Ca at higher pH are less soluble. A model was proposed where acidification and carbonation both lead to lower Ca2+and/or hydroxyl concentration, which removes Ca2+and hydroxyls from the romeite structure and leads to comparably higher Sb(V) concentration in equilibrium with romeite. Sb solubility depends on pH and Ca2+availability in this model, which has implications for bottom ash valorisation and risk assessment. © 2011 Elsevier Ltd.
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46. |
- Corvellec, Hervé, et al.
(author)
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The multiple market-exposure of waste management companies: A case study of two Swedish municipally owned companies.
- 2012
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In: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 32:9, s. 1722-1727
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Journal article (peer-reviewed)abstract
- This paper describes how the business model of two leading Swedish municipally owned solid waste management companies exposes them to four different but related markets: a political market in which their legitimacy as an organization is determined; a waste-as-material market that determines their access to waste as a process input; a technical market in which these companies choose what waste processing technique to use; and a commercial market in which they market their products. Each of these markets has a logic of its own. Managing these logics and articulating the interrelationships between these markets is a key strategic challenge for these companies.
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47. |
- Cui, Jirang, et al.
(author)
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Characterization of shredded television scrap and implications for materials recovery
- 2007
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 27:3, s. 415-424
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Journal article (peer-reviewed)abstract
- Characterization of TV scrap was carried out by using a variety of methods, such as chemical analysis, particle size and shape analysis, liberation degree analysis, thermogravimetric analysis, sink-float test, and IR spectrometry. A comparison of TV scrap, personal computer scrap, and printed circuit board scrap shows that the content of non-ferrous metals and precious metals in TV scrap is much lower than that in personal computer scrap or printed circuit board scrap. It is expected that recycling of TV scrap will not be cost-effective by utilizing conventional manual disassembly. The result of particle shape analysis indicates that the non-ferrous metal particles in TV scrap formed as a variety of shapes; it is much more heterogeneous than that of plastics and printed circuit boards. Furthermore, the separability of TV scrap using density-based techniques was evaluated by the sink-float test. The result demonstrates that a high recovery of copper could be obtained by using an effective gravity separation process. Identification of plastics shows that the major plastic in TV scrap is high impact polystyrene. Gravity separation of plastics may encounter some challenges in separation of plastics from TV scrap because of specific density variations.
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48. |
- Dahlén, Lisa, et al.
(author)
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Comparison of different collection systems for sorted household waste in Sweden
- 2007
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 27:10, s. 1298-1305
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Journal article (peer-reviewed)abstract
- Composition and quantity per person of municipal solid waste (MSW) have been analyzed in six municipalities in southern Sweden with similar socio-economic conditions but with different collection systems. Samples of residual waste have been sorted, classified and weighed in 21 categories during 26 analyses that took place from 1998-2004. Collection data of the total waste flow, including source sorted recycling materials, in the same area have been compiled and compared. Multivariate data analyses have been applied. Weight-based billing reduced delivered amounts of residual household waste by 50%, but it is unknown to what extent improper material paths had developed. With curbside collection more metal, plastic and paper packaging was separated and left to recycling. When separate collection of biodegradables was included in the curbside system, the overall sorting of dry recyclables increased. The large uncertainty associated with waste composition analyses makes it difficult to draw strong conclusions regarding the effects on specific recyclables or the changes in the composition of the residual waste.
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49. |
- Dahlén, Lisa, et al.
(author)
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Inconsistent pathways of household waste
- 2009
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 29:6, s. 1798-1806
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Journal article (peer-reviewed)abstract
- The aim of this study was to provide policy-makers and waste management planners with information about how recycling programs affect the quantities of specific materials recycled and disposed of. Two questions were addressed: which factors influence household waste generation and pathways? and how reliable are official waste data? Household waste flows were studied in 35 Swedish municipalities, and a wide variation in the amount of waste per capita was observed. When evaluating the effect of different waste collection policies, it was found to be important to identify site-specific factors influencing waste generation. Eleven municipal variables were investigated in an attempt to explain the variation. The amount of household waste per resident was higher in populous municipalities and when net commuting was positive. Property-close collection of dry recyclables led to increased delivery of sorted metal, plastic and paper packaging. No difference was seen in the amount of separated recyclables per capita when weight-based billing for the collection of residual waste was applied, but the amount of residual waste was lower. Sixteen sources of error in official waste statistics were identified and the results of the study emphasize the importance of reliable waste generation and composition data to underpin waste management policies.
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50. |
- Dahlén, Lisa, et al.
(author)
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Methods for household waste composition studies
- 2008
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 28:7, s. 1100-1112
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Journal article (peer-reviewed)abstract
- The question is how to conduct household waste composition studies. The review is divided into three parts: overview of known methods, sampling theory, and the waste components. Twenty methods are listed and commented on. There is no adopted, working international standard. In accordance with Pierre Gy’s Theory of Sampling, the seven types of sampling errors, when collecting and splitting solid samples, are described and commented on in relation to sampling of household solid waste. It is concluded that the most crucial choices in household waste composition studies are: to divide the investigation into relevant number and types of strata; to decide the required sample size and number of samples; to choose the sampling location, i.e., sampling at household level or sampling from loads of waste collection vehicles; and to choose the type and number of waste component categories to be investigated. Various classifications of household waste components used in composition studies are listed and discussed. Difficulties and weaknesses of the reviewed methods are discussed and concluded in suggested questions for further research.
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