| 1. |
- Dalemo, Magnus, et al.
(författare)
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Effects of including nitrogen emissions from soil in environmental systems analysis of waste management strategies
- 1998
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 24, s. 363-381
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Tidskriftsartikel (refereegranskat)abstract
- The environmental impacts of nitrogen emissions from soil resulting from the use of organic fertilizers, such as manure, are large compared with the corresponding impacts of mineral fertilizers. However, soil emissions are rarely included in systems analysis of waste management strategies. This study examines whether the inclusion of soil emissions can affect the environmental ranking of systems for managing solid biodegradable waste. Waste management scenarios based on incineration, anaerobic digestion and composting, respectively, were compared. The scenarios were analysed using the organic waste research (ORWARE) simulation model. A simplified model for calculating nitrogen availability and emissions was also constructed. Life-cycle analysis methodology was used for choosing system boundaries and evaluating the results. Global warming, acidification and eutrophication were the impact categories considered. The results indicate the vital importance of considering nitrogen emissions from soil when comparing biological waste management systems with other waste management methods, especially with regard to eutrophication effects. Soil emissions are also important when comparing the environmental impacts of anaerobic digestion and composting systems. However, the variation in nitrogen emissions from soil is large and depends on the spreading technique used, climate, drainage and soil texture
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| 2. |
- Dalemo, M., et al.
(författare)
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ORWARE – A simulation model for organic waste handling systems. : Part 1: Model description
- 1997
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 21:1, s. 17-37
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Tidskriftsartikel (refereegranskat)abstract
- A simulation model, ORWARE (ORganic WAste REsearch), for the handling of organic waste in urban areas has been constructed. The model provides a comprehensive view of the environmental effects, plant nutrient utilisation and energy turnover for this large and complex system. The ORWARE model consists of several sub-models; sewage plant, incineration, landfill, compost, anaerobic digestion, truck transport, transport by sewers, residue transport and spreading of residues on arable land. The model is intended for simulating different scenarios, and the results are: emissions to air and water, energy turnover and the amount of residues returned to arable land. All results are presented, both as the gross figure for the entire system and figures for each process. Throughout the model all physical flows are described by the same variable vector, consisting of 43 substances. This extensive vector facilitates a thorough analysis of the results, but involves some difficulties in acquiring relevant data. In this paper, the model is described. Results from a hypothetical case study are presented in a companion paper.
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| 3. |
- Menad, Nourreddine
(författare)
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Cathode ray tube recycling
- 1999
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 26:3-4, s. 143-154
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Tidskriftsartikel (refereegranskat)abstract
- Lead and polybrominated flame retardants are the two hazardous materials that can be found in electronic appliances. Particularly, cathode ray tubes (CRT) contain leaded glasses. In a computer monitor, over 98% of the lead is in the CRT. This material is generally not accepted for reuse as a component; only those from televisions can be reused. However, this currently represents only a very small market. Envirocycle (a US company) has developed a process to recycle all glasses contained in CRTs; this process includes cleaning and sorting glass. The product obtained is used for the manufacture of new CRT glass. Some industries have used pulverized glass from CRTs in smelting processes as slagging material instead of sand or slag. In this paper, some environmental issues related to the recycling of computers and television sets, and CRTs from computers are presented and discussed. Different processes used to recycle CRTs are described along with an economic analysis.
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| 4. |
- Menad, Nourreddine, et al.
(författare)
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Combustion of plastics contained in electric and electronic scrap
- 1998
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 24:1, s. 65-85
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Tidskriftsartikel (refereegranskat)abstract
- Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount up to 30% of the scrap mass. Generally, they contains flame retardants such as halogenated compounds which can lead to the formation of different toxic products. Recycling, incineration and landfilling are the current methods used to treat these plastics. They also can be used as combustibles in some metallurgical processes. However, during their combustion, halogenated flame retardants can produce dibenzop-dioxins and dibenzo-furans.
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| 5. |
- Menad, Nourreddine, et al.
(författare)
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Polyvinyl chloride used as a chlorinating and a reducing agent
- 1998
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 24:3-4, s. 257-274
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Tidskriftsartikel (refereegranskat)abstract
- Polyvinyl chloride (PVC) or vinyl is a recyclable material. It can be used as a chlorinating and a reducing agent. Two tests of chlorination and reduction of two different samples of jarosite and hematite were realized using PVC, results are presented in this paper. The chlorination test shows that the HCl gas produced from PVC and heated at ≈250°C can be used as a chlorine source to recover as chlorinated compounds the valuable metals such as Zn, Pb contained in jarosite. The XRD reveals the presence of lead and zinc chlorides in the condensates obtained. The second test of reduction was conducted using a mixture of PVC and hematite treated in a nitrogen atmosphere between 200 and 1000°C. The results show that at low temperature, PVC produces HCl and with kinetic consideration, no reactions can be observed with hematite. However, at high temperature, the weight of the hematite sample decreases by ≈15%, due to the reduction of hematite to iron metal.
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| 6. |
- Menad, Nourreddine, et al.
(författare)
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Thermal treatments of industrial wastes in controlled atmospheres for the elimination of As, Hg, Cd, Se and the concentration of Pb, Cu and Zn
- 1999
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 25:3-4, s. 233-254
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Tidskriftsartikel (refereegranskat)abstract
- Thermal treatments of five different types of non-ferrous metallurgical wastes, under a controlled atmosphere, were carried out at temperatures lower than 800°C for the separation of their toxic compounds and the concentration of valuable metals in the treatments residues. The best results were obtained by the treatments in air or hydrogen, or both successively. Simple treatments, using air or hydrogen, of three samples allowed the elimination of more than 95% of their toxic elements and almost doubled their valuable metals concentration. For the rest of the samples, a combined treatment was necessary for their efficient decontamination. In this case, the valuable metals content in the treatment's residue was increased to a reasonable value. Most of the solids issuing from these treatments can be recycled in current non-ferrous metallurgical processes.
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| 7. |
- Shen, H, et al.
(författare)
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A review of plastics waste recycling and the flotation of plastics
- 1999
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 25, s. 85-109
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Tidskriftsartikel (refereegranskat)abstract
- This paper summerizes the importance of plastic waste recycling and plastic waste separation. Based on an analysis of the physical and chemical characteristics of plastics and plastic waste, the potentials and limitations of several technological processes are discussed. In addition, a review of the surface chemical aspects of plastic flotation is presented. It can be concluded that the flotation of plasics is a fairly flexible technique and could prove to be a useful process for the separation of mixtures of several different types of plastics. however, more research and development effort is required before this technology can be introduced to industry.
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| 8. |
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| 9. |
- Zhang, Shunli, et al.
(författare)
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Aluminum recovery from electronic scrap by High-Force R eddy-current separators
- 1998
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 23:4, s. 225-241
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Tidskriftsartikel (refereegranskat)abstract
- The amount of electronic scrap which contains a substantial portion of non-ferrous metals, primarily copper and aluminum, has been growing. The present study is directed toward aluminum recovery by a newly developed eddy current separator. The investigation on shredded personal computer and printed circuit board scrap demonstrates that the High-Force® eddy-current separator will be applicable for this purpose. It has been shown that, by a single pass of the materials on the High-Force® eddy-current separator, an aluminum concentrate out of personal computer scrap can be obtained with a purity of 85%, while maintaining a recovery in excess of 90%, with the feed rate being up to 0.3 kg/min.
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| 10. |
- Zhang, Shunli, et al.
(författare)
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Mechanical separation-oriented characterization of electronic scrap
- 1997
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 21:4, s. 247-269
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Tidskriftsartikel (refereegranskat)abstract
- The ever-increasing amount of electronic scrap and the steadily-decreasing contents of the precious metals used in electronics, as well as the ever-growing environmental awareness, challenges such conventional precious-metal-oriented recycling techniques as pyrometallurgy. Separation and beneficiation of various materials encountered in electronic scrap might provide a correct solution ahead. In this context, mechanical separation-oriented characterization of electronic scrap was conducted in an attempt to evaluate the amenability of mechanical separation processes. Liberation degrees of various metals from the non-metals, which are crucial for mechanical separation, were analyzed by means of a grain counting approach. It is found that the metallic particles below 2 mm achieve almost complete liberation. Particle shapes were also quantified through an image processing system. The results obtained show that the shapes of the particles, as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation processes. In addition, separability of various materials was ascertained by a sink–float analysis. It has been shown that density-based separation techniques shall be viable in separating metals from plastics, light plastics (ABS, PS and PVC, etc.) from glass fiber reinforced resins and aluminum from heavy metals. Specifically, a high quality copper concentrate can be expected by density-based separation techniques. Moreover, FT-IR spectra of plastics pieces from the light fractions after the sink–float testing show that PC scrap primarily contains ABS, PS and PVC plastics with the density range of +1.0–1.5 g/cm3, whereas PCB scrap mainly contains glass fiber reinforced epoxy resins plastics with the density range of +1.5–2.0 g/cm3.
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