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MINIMIZING WASTE AMOUNT AND SAVING RESOURCES

MINIMIZING WASTE AMOUNT AND SAVING RESOURCES. Paper production. Chemical composition of wood. 50 % water Solid fraction : 45 % cellulose 25 % hemicellulose 25 % lignin 5 % other. Constituents of wood solid part (1).

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MINIMIZING WASTE AMOUNT AND SAVING RESOURCES

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  1. MINIMIZING WASTE AMOUNT AND SAVING RESOURCES

  2. Paperproduction

  3. Chemicalcompositionofwood • 50 % water • Solidfraction: • 45 % cellulose • 25 % hemicellulose • 25 % lignin • 5 % other

  4. Constituentsofwoodsolid part (1) • Cellulose (C6H10O5)n, n = 10000 to 14000 naturally, decreasedto 1000-3000 duringpulping • Degreeofpolymerization = n • Acid-hydrolysed • Hemicelluloseconsistsofdifferentsugarunits, branched and amorphous • Ligninishighly-branchedaromaticpolymer • Recalcitrantwaterpollutantin pulp and paperindustry Image: http://www.life.ku.dk/forskning/online_artikler/artikler/marken_en_stor_solfanger.aspx Image: Wikipedia

  5. Constituentsofwoodsolid part (2) • Extractives (hotwater/organicsolvents) • Terpenes, fats, fatty acids and alcohols, waxes and phenols, tannins • Addcolour and odourtowood, influenceitsphysical and mechanicalproperties • Resins – lipophylicextractives (non-polarorganicsolvents) • resin acids, long chain fatty acids, fats and volatile terpenes • Inorganic part • 0.2 to 1.0 % ofwood mass • calcium (40-70%), potassium (10-30%), magnesium (5-10%), iron (up to 10%), and sodiumcompounds

  6. Pulp and paperproductionstages

  7. Waterconsumption: stateofthe art Toproduce 1 t ofpaperwespendthefollowingamountsofwater: • 6 m3inpapermachineshowers • 2 m3forchemicalspreparation • 2 m3forsteamproduction • 2 m3for feed materialssolutions • 1 m3forvacuum pumps sealing • 2 m3incoolingtowers • Total: ca. 15-16 m3for1 t ofpaper

  8. Discharges: stateofthe art • Water used in wood handling/debarking/chipping • Barkhasmoreextractives (incl. phenols) and ligninsthanwood • Digester and evaporator condensates • White waters from screening, cleaning and thickening • Bleach plant washer filtrates • Paper machine white water • Fibre and liquor spills from all sections.

  9. Processwaterrecycle • Decreasesfreshwaterconsumption • Reduceswastewateramount • Producedwasteismoreconcentrated • Whitewater: fibre-enrichedwaterexitingpapermachine • Freshwaterconsumptionis 1-1.5 m3per 1 t ofpaperproduced

  10. Whitewatertreatment • Reducesdissolved and suspendedmatterbuild-upinprocesswater • Allowshigher pulp extractiondegree • UF/NF separatesorganiccompoundsand part ofsalts • Ozonedecomposesorganicmatter and desinfectswater • Wetairoxidationdegradesorganicmatter and desinfects

  11. Pros and consofclosedwatersystems • Advantages: • Decreasedwaterconsumption • Decreasedwasteamounts • Decreasedfibrelosses • Elevatedprocesstemperature • Disadvantages: • Build-upofsolids (dissolved and suspended), clogging • Morecomplicatedprocess • Corrosion • Productqualityissues • Unlesswewanttoiletpaper, freshwaterwouldhavetobeadded at 4 to 7 m3per tonne • Thismeans 2.5 to 5.5 m3pertonne ofwastewater • Elevatedtemperature

  12. Sulphuricacidproduction

  13. Contactreactor • H2SO4productionstages S + O2 SO2 SO2 + ½ O2 SO3 SO3+ H2SO4 H2SO4SO3 H2SO4SO3 + H2O  2 H2SO4 • Uses V2O5catalyst • 96 % conversionofSO2 • Ptismoreeffective, butisquicklypoisoned Image: http://www.dynamicscience.com.au/tester/solutions/chemistry/sulfuricacid.html

  14. Doublecontactreactor • 99.8 % SO2conversion • 0.003 vol. % of SO2in tail gas Image: http://www.greener-industry.org.uk/pages/sulphuric_acid/10SulphuricAcidDouble.htm

  15. Nitricacidproduction

  16. Ostwaldprocess and modifications 4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g) 2 NO (g) + O2 (g) → 2 NO2 (g) 3 NO2 (g) + H2O (l) → 2 HNO3 (aq) + NO (g) • NO hasverylowsolubility • Absorption NOxwithnitricacidsolution and wateraddition • Altering last phaseofthereaction: 2 NO2 + H2O2 → 2 HNO3 or4 NO2 (g) + O2 (g) + 2 H2O (l) → 4 HNO3 (aq) Image: http://chemistry.need.org/curriculum/fertilizer

  17. Phosphoricacidproduction

  18. Extraction H3PO4 Ca5(PO4)3X + 5 H2SO4 + 10 H2O → 3 H3PO4 + 5 CaSO4·2H2O + HX, X = -OH, -Cl, -Br, -I • CaSO4producedisreferredtoasphosphogypsum Image: http://www.fao.org/docrep/007/y5053e/y5053e0f.htm

  19. Phosphogypsum • Productionofsulphuricacid • Cement • Productionofammoniumsulphate • Productionofcalciumsulphide • Productionofsulphur and lime • Forfurtheruse, phosphogypsum must befreeofradioactiveelements present inmanyphosphateores • Treatingextractionphosphoricacidtoremoveradioactiveelementsmayalsobenecessary

  20. Electrochemicalprocesses

  21. ElectrochemicaldecompositionofNaCl NaCl + H2O NaOH + ½ H2 + ½ Cl2 • Diaphragmprocess • Mercurycellprocess • Membraneprocess

  22. Diaphragmprocess • Graphiteortitaniumanode, ironcatode • Diaphragm: asbestosfibresinpolymer (e.g. PTFE) matrix, resistsmigrationof OH-to Cl2-producing compartment • Product: 12 % NaOH, 16 % NaCl • Uponevaporation and crystallisation: 50 % NaOH, 1 % NaCl • Relativelylowvoltage, requireslesscleaninputbrine • Asbestos-associatedhazards, diaphragmcloggingbyCa/Mg, doesnotproducecleanNaOH Image: http://www.chemguide.co.uk/inorganic/group7/diaphragmcell.html

  23. Mercurycellprocess • Carbonanode, liquidHgcathode • Suppresseshydrogenproduction (req. 1.7-1.85 V overvoltage, actual – 1.2 V) • Produces 50 % NaOHwithuptoonly 30 mg L-1NaCl • Mercurytoxicityissues, pollution, formationofHg-organics Hg2+ + Na2S  HgS + 2 Na+ Image: http://electrochem.cwru.edu/encycl/art-b01-brine.htm Na+ + e- + n Hg NaHgn NaHgn + H2O  NaOH + ½ H2 + n Hg

  24. Membraneprocess Image: Wikipedia • Titaniumanode, nickelcatode, perfluorocarboxylic and perfluorosulfonicacid-basedmembrane • Membraneholdsbackanions • 40 % NaOHwithupto 50 mg L-1NaClproduced

  25. Currenttrends • Presently, themajorityofproductionswitchestomembraneprocess • Asbestos and mercurycompoundspollutionprevention • Qualityofproductunchanged Image: http://electrochem.cwru.edu/encycl/art-b01-brine.htm

  26. Ultra-low CO2steelmaking (ULCOS)

  27. Topgasrecyclingblastfurnace • Upto 26 % carboninputsaving • Upto 15 % CO2emissionreduction • Goal: 50 % CO2emissionsreductionby 2020 Image: http://www.ulcos.org/en/docs/Ref25%20-%20ULCOSpublic.pdf

  28. Surfacetreatmentinmetallurgy

  29. Surfacecoatingprocess • Stages • Degreasingwithsurfactantsolution • Surfactantsolutionremoval • Electrolyticsurfacecoating (Zn, Cu, Cr, etc.) • Rinsingbaths • Environmentalconcern: wastewaterswithelevatedamountsofmetals, manyofthemcarcinogenic (e.g. Ni, Cr6+) • Solution: precipitationashydroxides and sulphides • Reductionissometimesrequiredbeforeprecipitation (e.g. Cr6+ Cr3+) Image: http://www.protocase.com/products/mcf_chemconv.php

  30. Minimizingultimatewasteamountsinwastewatertreatment

  31. Paljassaare WastewaterTreatmentPlant, Tallinn Purifiedwaterpumpingstation Aerationtanks Secondaryclarifiers Sandgrids Primaryclarifiers Screens Main pumpingstation Image: Google Methane tank Sludgethickening and silos Wasteactivesludgethickening Mixedsludgestorage Stabilisedsludgestorage Image: https://aktal.tallinnlv.ee/static/Eelnoud/Dokumendid/ddok12933.htm Image: https://oigusaktid.tallinn.ee/?id=3001&aktid=119834

  32. Heatenergyreuse

  33. Heatrecuperationprinciples • Thermalwaste: e.g. cleanwaterwithevenslightlyelevatedtemperaturedischargedintowaterbody (why?) • Hotstreamexitingfromoneprocesscan serve as a heatsourceforanotherone Kansha et al., Chem. Eng. Sci. 65 (2010) 330-334

  34. Clusters

  35. Definition and types • Geographicalconcentrationofinterconnectedbusinesses, suppliers, distributors, etc. • Reasonsofclustersformation: • Commonnaturalresources, orcommonresearchfacilities (e.g. Silicon Valley, USA) • Geographicalproximitytomarkets (e.g. electronicsclusterin Guadalajara, Mexico) • Low-cost labor force • Know-howspreading • Fromcleanerproductionpointofview: • Lessresourcetransportation • Oneprocess’ productmaybeanotherone’s feed (e.g. fertilizerindustry and agriculture, coal and steelproductionin Ruhr, Germany) • Environmentmaybenefitwhenseveralcompanies at a timetryto solve pollutionquestionsintheiroperationregion

  36. Silicon Valley Image: http://www.startup-book.com/tag/cluster/

  37. Barets Sea Region

  38. Summary

  39. Cleanerproductionoptions • Efficientrinsing, incl. countercurrentrinsing • Materialsrecirculation • Heatrecirculation • Processintegration

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