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RECYCLING in waste management

RECYCLING in waste management

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RECYCLING in waste management

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  1. RECYCLING in waste management

  2. Totalwasteproductionin EU countries • Total amount of 2.62 billion tonnes (2008) • EuropeanParliament passed a resolution on ResourceEfficienEurope (zerowasteby 2020) Source: Eurostat

  3. Per capita waste generation in EU by individual countries

  4. Per capita hazardous waste generation in EU by individual countries

  5. Municipalsolidwaste (MSW) compositionin EU Total amount: 221 million tonnes

  6. MSW compositionforthe US Total MSW generation: 234 million tonnes Source: US EPA

  7. Stateofthe art: landfilling • Health and sanitaryrisks at dumpsites, and at theirvicinity (microorganisms, insects, rodents) • Groundwatercontaminationbylandfillleachate, incl. heavymetals and pesticides • Airbornepollution on burning and incineration • Releaseofgreenhousegases (CH4, CO2, etc.) • Theproblemcanbe at leastpartially solved byrecycling

  8. Recovery options for various waste: an American case study Thelowestrecovery: • Plastics • Foodwaste US EPA, 2005

  9. Recyclingdevelopment • Firstrecordedideas on recyclingoriginatedfromPlato (ca. 400 BC) • Archeology shows thatrecyclingwaspopularintheantiquity (why?) • 18th-19th centuries – recyclingofdust and ashfromburningwood and coal(bricks), scrapmetal, glass • WorldWars – literallyeverything • Nextupsurge – 1970s (greatlyincreasedpricesforoiland energy) • Increasedenvironmentalawareness

  10. Proposedcompleterecyclingscheme Collection Plastics Organics + rejects Sorting at conveyorbelt Composting Hard plastics Thin film plastics Glass Paper Metal Textile Compost Rejects Sand Press Crushing Bricks, interlocks, wheels, tables, manholes, road ramps, etc.

  11. Paperrecycling

  12. Paperrecyclingstages • Paper sorting • Metal removal by magnet (staplesetc.) • Pulping • Cleaning and screening • De-inking • frothflotation • washdeinking (detergentaddition) • Washing • Bleaching • Paperproduction • Itisconsidered (US EPA, 2012) thatpapercanberecycled 5-7 timesbeforecellulosefibresbecome too short

  13. Papersorting: mainpapercategories • High-gradepaperforprinting and writing • Newsprint • Paperboard and packagingpaper • Tissues and papertowels • De-inkingisrequiredformostpapertypesincourseofrecycling

  14. Pulping and screening • Mechanicaldefragmentation • pHadjustedto 8.5-10 • H2O2 / O3forbleaching • Ca2+ compunds as fillers • Fattyacids/soap • Obtainedslurryundergoescentrifugalcleaning and screeningtoremoveparticlesheavier and largerthan pulp fibres

  15. De-inking: frothflotation • Chemicalscanbeaddedtofaciliateinkremoval • Thisisdoneprimarilyintissuepaperproduction Image source: en.wikipedia.org

  16. Recycling 1 t ofpapersaves: • 1 t of wood (ca 17 trees) • 26 m3 of water • 320 L of oil • 4100 kW h of energy (6-months consumptionofanaverage US house) • 2.3 m3 of landfillspace

  17. Plasticrecycling

  18. Mostcommonlyusedplastictypes • PET/PETE (polyethyleneterephtalate) – soft drink bottles, foodcontainers • HDPE (highdensitypolyethylene) – bottlesforbeverageswithshortlife (milk, juices) • LDPE (low-density PE) – cableinsulation, flexiblebottles • PVC (polyvinylchloride), V (vinyl) – packagingsheets, wire and cableinsulation, floor tiles • PP (polypropylene) – packaging film, bottlesforhotliquids • PS (polystyrene) – protectivepackaging

  19. Basic recyclingsteps Plasticwaste • Cleaning (hotwater) • Sorting • Cutting • Shredding • Agglomeration • Pelletizing • Reprocessing Washing Sorting Agglomeration Shredding Pelletizing Extrusion Film blowing Injectionmolding

  20. Sortingplastictypes • Water-alcoholsolution: •  = 925 kg m-3: HDPE sinks, PP floats •  = 930 kg m-3: HDPE sinks, LDPE floats • Water-saltsolution: - separating PS (polystyrene) and PVC • Resinidentificationcode (RIC) • Near-infraredanalysis (NIR)

  21. Resinidentificationcode PET PP HDPE PS PVC Other LDPE

  22. A fewwords on infraredanalysis Graph: Khayet et al., J. Membr. Sci. 263 (2005) 77-95 Spectrometers: Google

  23. Extrusion • rotatingscrew • plasticpelletsaddition • breakerplate • extrudedplastic Image source: en.wikipedia.org

  24. Injectionmolding

  25. Film blowing http://www.hipf.edu.sa/HIPF_English/Courses-BFE.html

  26. Thermaldepolymerisation (TDP) • Plasticwasteiscutorshredded • Wateraddition • Temperaturerisento 250 C at constantvolume, pressurerisesto 4 MPa, 15 min • Pressureisreleased, waterevaporates • Secondstagereactor: 500 C, breakinguplonghydrocarbonchains • Destillation • Light crude oil produced • Plasticbottlescanproduceupto 70 % oil and 16 % gasesfromtheirinitial mass

  27. Products from recycled plastic • PET: • Storage containers, including food containers, fabrics • HDPE • Tables, roadside curbs, benches, truck cargo liners, trash receptacles • PS • Metal casting operations, concrete • Others • Bricks, tiles, plastic railroad ties, additives to ashalt

  28. Glassrecycling

  29. Main glasstypes • Containerglass • Flatglass • Fibreglass • Domesticglass • Specialglasstypes: fusedsilica, borosilicateglass, etc.

  30. Glasscomposition (1): • Soda-lime-silicaglass: 72% SiO2, 14.2% Na2O ,2.5%MgO, 10.0%CaO, 0.6%Al2O3; highthermalexpansion, lowheatresistance (melts at 500-600 C) – windows, containers, glassware, etc. • Borosilicateglass (incl. Pyrex): 81% SiO2, 12%B2O3, 4.5% Na2O, 2.0%Al2O3; verylowthermalexpansion – laboratoryware, optics, householdcookware • Fused/vitreoussilicaglass: SiO2; lowthermalexpansion, veryhard, resistsheat (melts at 1000-1500 C) and weathering – furnacetubes • Crystalglass: 59 % SiO2, 2.0 % Na2O, 25 % PbO, 12 % K2O, 0.4 % Al2O3, 1.5 % ZnO; highelasticity, poor heatresistance - glassware

  31. Glasscomposition (2) • Aluminosilicateglass: 57 % SiO2, 16 % Al2O3, 4.0 % B2O3, 6.0 % BaO, 7.0 % MgO, 10 % CaO – fibreglass, glass-reinforcedplastics, halogenbulbglass • Oxide glass: 90%Al2O3, 10%GeO2;extremely clear, used for fibreoptics

  32. Glassrecyclingstages • Sorting • Bycolour: glassofdifferentcolourgenerallyhasdifferentproperties • Byglasstypes – borosilicate and otherspecialglasstypesshouldbedealtwithseparately: theseshouldbedisposedofseparately • Crushingintocullet • Melting • Production • Part of glasscontainerscanbereused

  33. Optical glass separator

  34. Glassproduction • Glass and culletstorage • Meltinginfurnace (upto 1575 C) • Forming • Cuttingmoltenglassintocylindersa.k.a. gobs (1050-1200 C) • Blow and blowmethod: glassisblowninto ring mouldwith all thecontainerdetails (parisons), and thenblowntofullcontainershape • Press and blowmethod: parisons are formedby pressing • Donebyindividualsection (IS) machines • Innersurfacedealkalization (high-temperature S- and F-containinggas) • Annealing (580 C) • Coolingdown (20-6000 min)

  35. Foamglassproduction • Foaming agent isaddedtotheglass • CaSO4 • Coal • CaCO3 • Aluminiumslag • Mixing (foaming agent particlesize ca. 75-150 µm) • Heating: gasbubblesform and expand (700-900 C) • Annealing • Cuttingintodetails

  36. Implementation of recycled glass • Glassware • Insulation • Ceramic sanitary ware • Brick manufacturing • Artificial turf • Recycled glass worktops • Foam glass filters • Abrasive materials • Construction aggregate for concrete

  37. Laminated plastic recycling

  38. Laminated plastics • Usually a plastic made of superposed layers of paper, wood, glass, metal or fabric bonded or impregnated with resin and compressed under heat • Perhaps one of the most challenging material in terms of recycling is PE/Al composite (chip bags, milk/juice containers, etc.)

  39. Recycling process stages • Shredding • Magnetic and Foucaul current separation • Foucault or eddy curent arise when the magnetic current passing through conducting material changes • This slows down passing metallic objects • Aluminium-rich fraction (up to 50 %) is thus obtained • Fraction is treated thermally to remove PE • Rotating kiln • Moving bed pyrolysis oven • Al is remelted and recycled into new foil

  40. Alternative recovery • Shredding • Addition of diluted acid (HCl or H2SO4) or NaOH 2 Al + 6 HCl → 2 AlCl3 + 3 H2 ↑ 2 Al + NaOH → 2 NaAlO2 + H2 ↑ • PE slurry is separated by filtration • Hydrogen can be used as fuel gas

  41. Biodegradable organic waste recycling (including food waste)

  42. Organic part recycling • Anaerobic fermentation coupled with biogas production • Methane tanks • Optimal temperature for biogas production is around 37 °C • Composition: methane and carbon dioxide, may have hydrogen • Composting • Sludge from methane tanks isaerated, dewatered (whennecessary), and mixed withpeat (whennecessary) • Left for further decomposition • Used as soil for food-unrelatedpurposesuponrejectsremoval (ifany)

  43. Recycling MSW rejects

  44. Rejects • Contaminated plastic bags • Clening not cost efficient • Small pieces of glass • May be dangerous for those who sort waste • The rejects are usually separated from compost after maturation of piles • Drum separator with cutting tools • Organic material is shredded into smaller prices an exits through openings in drum walls • Rejects are transported further and exit at the end of the drum • Alternative: screen separator • Can be incinerated or recycled

  45. Separated rejects Compost with rejects • Agglomeration • Cutting • Sand addition • Heating up to 140-240 °C • Plastic rejects melt, forming silica-plast mass that can be molded and pressed into various products Compost Separator Sand Rejects Sand screens Agglomerator Mixing and heating Mold Products Hydraulic press

  46. Silica-plast products from MSW rejects • 20-60 % of sand • Compressivestrength 10-23 Mpa • Densityof 1.12-1.68 g cm-3 • Lowwateradsorption • Bricks • Poor adhesion (plastic) • Higherdensity • Hardmaterial (bulletproof) • Interlocks • Yards, floors, pavements, etc. • Costis 30-50 % ofceramicinterlocks • Maintenanceholecovers • Cheaper and notpronetocorrosion, asmetalcovers

  47. Recycling in iron and steel industry

  48. Blastfurnace • Hotblast • Meltingzone • FeOreduction • Fe2O3reduction • Pre-heating • Feed • Exhaustgases • Ore, coke and limestone • Removalofslag • Moltenpigiron • Wastegasescollection Fe2O3 + 3CO → 2Fe + 3CO2

  49. Pigiron • 2.14-6.97 % C • 0.2-0.8 % Si • 0.08-0.18 % P • 0.01-0.04 % S • Mn, etc. • Brittleduetohighcarboncontent • Refinigintosteelisneeded

  50. Basic oxygenfurnace • Hotpigironispouredintoconverter • Magnesiumforsulphurremoval • Oxygenstream (99 %) • Outcome: low-carbonsteel • 0.3-0.6 % C • 0.05-0.1 % Mn • 0.01-0.03 % Si • 0.01-0.03 % S and P