| Abstract [eng] |
Up to this day waste incineration and energy generation from it takes a big part of waste management decisions. Even though waste incineration is not considered a top priority, this waste treatment solution is much more environmentally friendly than waste disposal in landfill. In incineration waste can lose up to 20 times of its volume and the main residue after incineration are bottom ash and slag. In this Master’s Final Degree Project research has been made to analyse non-hazardous waste incineration residues bottom ash and slag generated from Kaunas cogeneration plant. Because of relatively recent start of non-hazardous waste incineration, in Lithuania there is not enough research made that determine bottom ashes and slag’s elemental and mineral composition in addition with heavy metal leaching values from environmental perspective. One of the main goals of this research: determine the potential of these waste residues to be used in civil engineering as a construction material. In this project research elemental composition of bottom ash and slag were determined, most abundant elements were oxygen, calcium, silicon, iron, aluminum, sodium, carbon, potassium, and magnesium. A smaller part of elemental composition consisted of titanium, sulfur, chlorine and phosphorus. Because of bottom ash and slag heterogeneous nature, with different granulometric size fractions elemental composition was not the same, but the highest portion of all fractions consisted of the above – mentioned elements. After determining bottom ash and slag mineralogical composition, it was found that it consists of mineralogical modifications such as: quartz, barium – bismuth – lead oxide, potassium – magnesium silicate, aluminum oxide and calcium carbonate. When aging processes take place, from other identified mineral compositions expected modifications are calcium sulfates hemihydrate’s reaction with water to form gypsum; iron oxidation in magnetite; calcite reaction with acidic precipitation. After moisture content investigation test it was determined that more moist ash and slag were from smaller granulometric fraction, while relatively less moist were larger granulometric mineral fractions. For the before mentioned ash metal leaching research, distilled water and “royal water” (hydrochloric and nitric acid mixture) were used. In the research study it was determined, that in many cases leaching from treated ash and slag did not depend on granulometric size of the fraction. Based on the research study results using distilled water for heavy metal leaching, overall, these materials could be used in civil engineering, because the leached concentrations were not high and did not exceed ashes and slags determined handling regulations by environmental protection requirements limit values. |
