Screening analysis of bottom ashes from waste incinerationA local waste-to-energy plant in Northern Sweden incinerates municipal solid waste (MSW). The bottom ash (BA) shall be used as construction material. To investigate the homogeneity of the BA, as a base for a more detailed characterisation, a screening was done on 0-10 mm samples taken daily during one month in an ash treatment plant for metal separation.The on-going characterisation focuses on the leaching of heavy metals from the BA as previous work (Oja 2012) showed that a number of trace metals (As, Cd, Cr, Cu, Ni, Pb and Zn) exceeds the limits set up by the Swedish EPA (Naturvårdsverket 2010) for the use of waste as construction material with regard to total content. Since Cu and Cr also exceed the leaching limits (L/S10), the bottom ash cannot be used without treatment. Ageing and the effect of immobilising amendments are studied with regard to their effect on the leaching behaviour.Material and MethodSamples of BA were taken after metal separation and sieving, daily during one month in 2012 resulting in 32 samples of two different fractions, 0-10 mm and 10-50 mm. A screening was performed on the 0-10 mm fraction analysing pH, EC both in duplicates and LOI, TS, and elemental composition using XRF on non-milled samples in triplicates. Results Based on the analyses made, no grouping of samples could be observed (figure 1), and therefore the material in each fraction was homogenized prior to further investigation. On-going studyDifferent treatment options such as accelerated ageing and stabilization with e.g. zero valent iron are investigated in an on-going study. Also, the effect of incineration parameters such as temperature, air flow and time, on the composition of the BA is studied through modelling (using Factsage). The overall goal is to improve the quality of the BA to an extent that it can be used in different ground constructions.The combined effects of weathering and iron amendment on the mineral composition and the leaching behaviour will be studied. The test program includes acid neutralization capacity (ANC), TOC, XRF, XRD analyses and a column test. Mechanical stability and freeze-thaw resistance will also be tested. Using the Factsage database the incineration process will be modelled with regard to possible changes in the composition of the BA.In addition to this work two field test areas (á 200 m2) will be installed using treated BA as base layer in a material processing and stockpile areas. The leachate will be collected using lysimeters and analysed monthly. Primary results will be available in late summer/early fall. References Naturvårdsverket (2010). Återvinning av avfall i anläggningsarbeten. Handbok 2010:1. Naturvårdsverket StockholmOja E. (2012). Botten aska som dräneringsskikt vid sluttäckning av deponier. Department of Environmental Engineering, Division of Waste Science and Technology, Luleå University of Technology