Mekanisk och biogeokemisk karaktärisering av mekaniskt upparbetad deponirest: Vid Ragn-Sells Avfallsbehandling AB:s avfallsanläggning Högbytorp i Upplands-Bro
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
In this master thesis, the mechanical and biogeochemical properties of a mechanically treated waste from Högbytorp Landfill (owned by Ragn-Sells avfallsbehandling AB) were characterized. The mechanical treatment involves fresh and excavated domestic and industrial waste that undergoes shredding, sorting of metals, and sorting of combustible materials by screening. The waste will afterwards be deposited back into the landfill. The aim with the mechanical treatment is to reduce the organic content, reduce the volume, reclaim recyclable materials and regenerate landfill area. The treated waste that was characterized had a particle size < 18 mm. During sampling the japanese slab-cake method was applied together with the use of a riffle splitter. The mechanical properties that were characterized were friction angle, grain size distribution, shear strength, compression, density, swelling pressure, field capacity and permeability. Generally, tests were performed according to standards, but the compression test was performed by custom-made compressions vessels with a diameter of 50 cm. After the compression test was finished also values on density, porosity, swelling pressure and field capacity were derived. The permeability test was made by connecting water to the compression vessels. The results from the mechanical characterization showed in comparison to earlier studies on municipal solid waste: • High shear strength (c´ 26 kPa, Φ´ 47°), porosity (η 53 %), field capacity (54 %), density (ρ 0.65 ton/m3, ρd 0.32 ton/m3 at 0 kPa and ρ 1.5 ton/m3, ρd 1.0 ton/m3, ρs 2.1 ton/m3 at 700 kPa). • Normal compressions index (m 0.19) and friction angle (31.7°). • Low swelling pressure (0 kPa) and permeability (k 6.7 × 10-9 m/s), and a small grain size distribution with a high uniformity coefficient (Cu 40). The mechanical property that mainly should be considered during landfilling is the low permeability of the waste which can cause stability problems if pore water pressure is built up due to non-satisfying drainage. Meanwhile the material exhibited difficulties in packing at high water content and the TS should therefore during compaction exceed 48 % with a good margin. The biogeochemical characterization comprised composition of the waste, leaching behavior and gas formation potential. The composition of the waste was characterized with respect to TS, organic content and total content of elements. Leaching tests were performed to produce leachate from the compression vessels at L/S ratio 0.6 and leachate from agitation batch tests at L/S ratio 10. Agitation batch tests were performed under anaerobic conditions in order to simulate methanogen degradation phase. In addition, water from impervious surfaces where the mechanically processed waste will be treated, was analyzed. The result of the biogeochemical characterization revealed that the mechanically treated waste, in comparison to other studies on fresh and excavated waste, had low TS (47 %), low to normal organic content (15 % TOC) and a high total content of metals. When compared to applicable threshold values for nonhazardous waste it was evident that the organic content was high in general. Both the total content (as TOC) and the concentrations in the leachate (as DOC) at L/S ratio 0.6 and 10 exceeded the threshold values. Other threshold values that were exceeded in the leachate were antimony and zinc. In storm water the concentration of several elements exceeded what had previously been reported in surface water from traditional municipal solid waste. The reason was assumed to be due to crushing of the waste. The total content of several metals exceeded the guideline values for less sensitive land use, given by the Swedish Environmental Protection Agency. In contrast to what previous studies on mechanically treated waste has shown the mechanically treated waste in this study is not suitable as construction material for offsite applications. The low permeability was measured under high compression and a possible reuse as liner material in the upper parts of a landfill is therefore considered not as an option. Though, the high field capacity indicates a possible reuse as protection layer in landfills.
Place, publisher, year, edition, pages
2013. , 345 p.
Teknik, Deponi, Avfallsteknik, Geoteknik, Geokemi
IdentifiersURN: urn:nbn:se:ltu:diva-56623Local ID: d6277e9a-f4ab-440d-ad4d-4ed2b9596007OAI: oai:DiVA.org:ltu-56623DiVA: diva2:1030010
Subject / course
Student thesis, at least 30 credits
Civil Engineering, master's level
Validerat; 20130528 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved