Content of heavy metals in reed ash and possibilities of reed ash utilization
2016
Cubars, E., Rezekne Academy of Technologies (Latvia) | Poisa, L., Latvia Univ. of Agriculture, Jelgava (Latvia)
Reed growths are important regulators of the content of heavy metals in water bodies and silt. While growing, reed captures heavy metals, therefore it can be considered that the extraction of reeds would facilitate removal of heavy metals from water bodies. However, after burning reeds, heavy metals would remain in a concentrated amount in reed ash. Reed ash could be disposed by incorporating them in the soil, but the content of heavy metals that would determine the maximum allowable dose of ash dispersion is not known. It raises the need for further studies on this issue. To determine the maximum 5-year dose of ash that can be dispersed in 1 hectare of soil, maximum values of heavy metal content in reed ash were chosen, by using limiting values of heavy metal content determined for sewage sludge. Analysis of heavy metal content was carried out in relation to chrome (Cr), copper (Cu), cadmium (Cd), nickel (Ni) and lead (Pb). The analysed reed samples were taken from 11 natural and artificial water bodies in Latvia, whose resources of reeds are considered to be significant. It was found that the main heavy metal in reed ash that limits the dose of ash dispersion in the soil is Cr, the maximum 5-year dose for reed ash dispersion in sandy, sandy clay soil constitutes 14.3 tons of ash per hectare, while in loam and clay soils it amounts to 16.6 tons, which is more than in wood ash. Therefore, it can be concluded that in case of burning crushed reed together with wood, maximum reed ash dispersion dose would be greater than the dose of wood ash, and thus it would require smaller soil areas for ash disposal.
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