Properties of biofuel fly ash and capabilities of its use for agricultural needs
¹Lithuanian Energy Institute, Laboratory of Heat–Equipment Research and Testing, Breslaujos st. 3, LT-44403 Kaunas, Lithuania
²UAB ‘Enerstena’ Centre of Research and Development, Ateities pl. 30A, LT-52163 Kaunas, Lithuania
The use of various types of biomass for energy production provides great prospects for reducing the consumption of fossil fuels and the negative impact on the environment. However, the use of biomass, in particular agromass for this purpose, results in relatively large amounts of bottom ashes and fly ashes, the composition and properties of which also raise a number of additional environmental problems. The composition and properties of fly ash are investigated in the paper, taking into account the possibilities of utilizing them for soil fertilization and other applications. Fly ash samples were collected from bunkers of flue gas cleaning equipment (electrostatic precipitator and cyclones) installed after water heating boilers, which are firing wood chips and chuffed straw. The composition of fly ash was determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) while particle size distribution was obtained using scattered-light aerosol spectrometer. Electrical Low Pressure Impactor (ELPI) was used to separate fly ash into 14 groups by particle diameter, and the analysis of their composition showed differences in the composition of the fly ash collected in cyclones and Electrostatic Precipitators (ESP). An analysis of the composition of samples in regard to the existing heavy metals norms and considering concentrations of elements beneficial to the growth of plants, enables to prepare recommendations for fertilization. The determined alkalinity of fly ash pH 13 confirms the possibility of their use for reducing soil acidity. The analysis of fly ash composition has shown that they contain elements, important for plant growth (Ca, Mg, K, P, N, S), and their concentrations determine the further use for soil quality improvement because the amount of these elements in the acid soils is reduced.