Accelerate ageing of refuse-derived-fuel (RDF) fly ashes

Ashes have properties that can be exploited in various applications, e.g. some ashes can be used in the construction of barriers in a landfill final top cover. A landfill top cover is a multilayer construction that protects the environment in several ways, for instance hindering gas emissions from the landfill body and water infiltration into the waste.Impervious natural materials like clay, synthetic materials like geomembranes or bentonite carpets, geosynthetic clay liners or combinations of such materials are commonly used in landfill top cover constructions. Since differential settlement may occur and the lifetimes of the synthetic materials are uncertain, it is advantageous to use thick mineral constructions. There is a great need for these materials, and substantial savings of resources can be made if alternative waste materials, like ashes, are used. Currently, ashes are either landfilled or used as construction materials. They are subject to weathering processes, including physical, chemical and mineralogical changes caused (inter alia) by fluctuations of temperature and humidity, atmospheric gases or acid rain. Ashes contain various potentially hazardous and non-hazardous chemical compounds. Therefore, precautions must be taken to avoid leaching of substances such as heavy metals into the surrounding environment. Mineral phases that are initially present and/or that form during the ageing are primarily responsible for the immobilization or leaching of diverse metals and salts. Newly formed mineral phases like clay minerals are of main interest, because of their very high cation exchange capacity, swelling and expansion properties.The conditions found in a landfill environment are likely to favour clay mineral formation. This thesis is based on studies on the effects of accelerated ageing on refuse-derived-fuel (RDF) fly ashes, in experiments under controlled laboratory conditions, intended to derive models to predict the stability of RDF fly ashes used in a landfill liner and the mineralogical changes that occur in them. A reduced factorial design was applied, followed by multivariate data analysis, to evaluate the effects of five factors - carbon dioxide (CO2) levels, temperature, relative air humidity (RH), time and the quality of added water - on mineral transformations within the ashes, and their acid neutralization capacity (ANC) and leaching behaviour.Minerals (ettringite and hydrocalumite) promoting the immobilization of hazardous compounds were found in both fresh ash and ash aged under atmospheric conditions, but these minerals disappeared upon carbonation. The main phases in ash at 20% and 100% CO2 were calcite, gypsum/anhydrite and vaterite. The abundance of gypsum and anhydrite was directly related to the temperature at which ashes were aged. The major mineral phases detected in ashes aged under 20% CO2, 65% RH and 30°C (corresponding to conditions generally found in a landfill cover) were calcite and gypsum/bassanite. The pH values of these ash specimens ranged from 7.2 to 7.6, indicating advanced carbonation. Ageing decreased pH values from 12.4 to 7.2, consequently affecting the leaching behaviour of most chemicals measured in the leachates. Levels of Ba, Ca, Cl, Cr, Cu, Pb, K and Na decreased over the study period while those of Mg, Zn and SO4 increased. No clay minerals were detected by XRD and SEM analysis in either fresh or aged ashes. However, geochemical modelling indicated that such minerals may precipitate. The modelling also indicated that clay minerals like saponite, vermiculite, chrysotile and hydrotalcite were likely to precipitate in most leachates from ash aged for 3, 10 and 22 months. Smectite, montmorillonite and illite may precipitate in leachates of ash aged for 31 months. The formation of smectite, montmorillonite and vermiculite would be advantageous due to their very high cation exchange capacities, which would favour the stabilization/immobilization of heavy metals in the mineral phases.Askor har egenskaper som kan användas, en del askor kan t ex användas vid konstruktion av tätskikt i en deponisluttäckning. En deponisluttäckning är en flerskiktskonstruktion som skyddar miljön från t.ex. växthusgaser från deponin och hindrar vatteninträngning till avfall. Naturliga täta material som lera, syntetiska som geomembraner eller bentonitmattor eller en kombination av dessa är vanligt förekommande i sluttäckningskonstruktioner på deponier. Eftersom differentialsättningar kan uppkomma och de syntetiska materialens livslängd är osäker, är det en fördel om tjocka mineraliska konstruktioner kan användas. För dessa är materialbehovet stort och det är en stor resursbesparing om alternativa material, som aska, kan användas.Aska utsätts för åldringsprocesser både när den deponeras eller användas som byggmaterial. Materialet genomgår fysiska, kemiska och mineralogiska förändringar orsakade av t.ex. variationer av temperatur och luftfuktighet, atmosfäriska gaser eller surt regn. Aska innehåller olika farliga och ofarliga kemiska föreningar. Därför måste försiktighetsåtgärder vidtas för att undvika läckage av tungmetaller i miljön. Befintliga och nybildade mineralfaser är främst ansvariga för immobilisering eller utlakning av olika metaller och salter. Nybildade mineralfaser som lermineraler är av stort intresse på grund av deras mycket höga katjonutbyteskapacitet, svällnings- och expansionsegenskaper. Förhållandena som råder i en deponisluttäckning förväntas gynna lermineralbildning.Denna avhandling är resultatet av studier av effekten av accelererad åldring på flygaska från energiutvinning. För att förutsäga stabiliteten i flygaska som används i ett deponitätskikt har laboratorieexperiment utförts för att studera effekterna av accelererad åldring under kontrollerade förhållanden. Ett reducerat faktorförsök har gjorts för att utvärdera påverkan av fem faktorer: koldioxid (CO2), temperatur, relativ luftfuktighet (RH), tid och kvalitet på tillsatt vatten. Inflytandet av dessa faktorer på mineralomvandlingen i askan, askans syraneutraliserande förmåga (ANC) och urlakningsbeteendet har analyserats och utvärderats med hjälp av bl a multivariat dataanalys. Mineraler (ettringit och hydrocalumit) som främjar fixeringen av farliga ämnen finns i både färsk aska och prover som åldrats under atmosfäriska förhållanden men försvann efter karbonatisering. Aska som åldrats under 20 % och 100 % CO2 hade kalcit, gips / anhydrit och vaterit som huvudmineraler. Förekomsten av gips och anhydrit var direkt relaterad till temperaturnivån som askan hade åldrats i. Aska som åldrades under 20 % CO2, 65 % RH, 30 °C temperatur (motsvarande förhållandena i en deponitäckning) hade kalcit och gips/bassanit som huvudmineraler. pH-värdena i proverna varierade från 7,2 till 7,6 vilket indikerar en långt fortskriden karbonatisering. Åldrandet sänkte pH-värdena från 12,4 till 7,2 och påverkar därmed urlakningsbeteendet för många lakvattenkomponenter. Barium, Ca, Cl, Cr, Cu, Pb, K och Na minskade under tiden, medan Mg, Zn och SO4 ökade jämfört med den färska askan. Inga lermineraler upptäcktes med hjälp av XRD och SEM i varken färsk eller åldrad aska. Geokemisk modellering visade dock möjligheten för dessa mineraler att bildas och fällas ut. Lermineraler som saponit, vermikulit, krysotil och hydrotalcit kunde enligt beräkningarna bildas i lakvatten från de flesta proverna som åldrades i 3, 10 och 22 månader. Smectit, montmorillonit och illit kan bildas i lakvatten från 31 månaders åldrad aska. Bildning av smectit, montmorillonit och vermikulit skulle var värdefull på grund av deras mycket höga katjonutbyteskapacitet, vilket gynnar stabilisering / immobilisering av tungmetaller i askan.Godkänd; 2010; 20101020 (evebra); LICENTIATSEMINARIUM Ämnesområde: Avfallsteknik/Waste Science and Technology Examinator: Professor Anders Lagerkvist, Luleå tekniska universitet Diskutant: Professor Britt-Marie Steenari, Chalmers tekniska högskola Tid: Onsdag den 17 november 2010 kl 09.30 Plats: F1031, Luleå tekniska universitet</p

Suitability of fly ash for construction and land applications

Municipal solid waste incineration fly ash is often landfilled or sent abroad for stabilization because it is considered a hazardous waste. These approaches to fly ash are both costly, and highlight the need for alternative and sustainable ash recycling. Both the needs of waste recycling and preservation of natural resources can be solved by using fly ashes as a secondary construction material and as soil fertilizer.Three types of fly ashes have been investigated in the laboratory experiments. Namely municipal solid waste incineration (MSWI), refuse-derived-fuel (RDF) and biofuel fly ashes. Factors influencing changes in chemical properties and mineralogical composition of RDF fly ash exposed to environmental conditions close to those that are found in a landfill top cover were evaluated in the accelerated ageing experiment. Element availability to leaching and plant uptake in soil amended with MSWI, biofuel fly ashes and biosolids was also evaluated.RDF fly ash exposed to the conditions found in a landfill top cover (20% CO2, 65% RH, 30°C T) lead to the chemical and mineralogical transformations that resulted in reduced leaching of most of the elements studied here. Only concentrations of Cl- in the leachates were an issue, because they still exceeded the leaching limit values; nevertheless the leaching of this element in aged ash decreased by 50% compared to fresh ash.Application of pelletized MSWI fly ash with biosolids on soil resulted in elevated total concentrations of As, Cd and Pb in soil (by 29%, 100% and 300%), but dissolved concentrations of these elements in soil pore water, except the As, were low as in the range of drinking water concentrations (98/83/EC). Furthermore, the concentrations of Cd and Pb in plant biomass were negligible regardless of the type of ash used.Based on the observations, RDF fly ash is considered as a suitable material to be used in a landfill liner. Whereas MSWI and biofuel fly ashes based on element availability for plants studies, could be considered suitable for land applications. But doses to be applied on soil should be adjusted to the type of ashes used to avoid accumulation of potentially toxic elements in soil over time.Godkänd; 2013; 20130827 (evebra); Tillkännagivande disputation 2013-10-04 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Evelina Brännvall Ämne: Avfallsteknik/Waste Science and Technology Avhandling: Suitability of Fly Ash for Construction and Land Applications Opponent: Associate Professor Alessandra Polettini, University of Rome ”La Sapienza”, Rome, Italy Ordförande: Professor Anders Lagerkvist, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 25 oktober 2013, kl 10.00 Plats: F1031, Luleå tekniska universite

Leaching properties of steel slags after ageing under laboratory and field conditions

Godkänd; 2010; 20120110 (andbra

Characterisation of waste material mixtures for landfill top cover application

Godkänd; 2012; 20120614 (ysko)</p

Mobility of redox sensitive elements due to organic matter in contaminated soil : bottom ash and residual waste fraction

Godkänd; 2012; 20120614 (ysko

Spatial variability of topsoil contamination by trace elements on the territories of kindergartens in Vilnius, Lithuania

Godkänd; 2009; 20090807 (juku

Evaluation and discussion of steel slag mineralogy after ageing under laboratory and field conditions

Godkänd; 2010; 20100909 (evebra

The profession of research management and administration in Sweden

This chapter outlines the development of the Swedish Higher Education System that led to the evolution of the profession of research management and administration (RMA) in Sweden. Evolution from an informal network towards more formalised and structured work within the Swedish RMA community is highlighted. Discussion on the level of salaries development depending on the education level, gender, experience and roles are elaborated too. The majority of the Swedish RMA community are women, which does not differ from most other RMA communities around the world. Swedish Association of Research Managers and Administrators (SWARMA) is the bridge between national research and innovation funding agencies and researchers. SWARMA selected members actively participate in the reference groups for EU R&amp;I programmes. The future for RMAs in Sweden looks bright!. © 2024 by Eva-Lisa Ahnstrom, Evelina Brannvall, Ylva Hultman and Anders Jonsson. All rights reserved

Effect of residue combinations on plant uptake of nutrients and potentially toxic elements

The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake. Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534 mg/l), Mg (184 mg/l), P (1.8 mg/l), S (760 mg/l), Cu (0.39 mg/l) and Zn (0.58 mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82 g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values. The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low