Torefakcia biomasy (energetických travín).

Abstract

This thesis is focused on the identification of suitable conditions for the torrefied carbon obtention from nine kinds of energy grasses. Thesis deals also with the possibilities of soil properties improving (controlled release of nutrients and limitation of heavy metals migration) by produced torrefied carbon (biochar). The biomass – energy grasses were chosen for the research because of the current agricultural situation. Nowadays the amount of breeding animals decreases, thus it leads to the grass/hay overproduction. It is necessary to find a suitable utilization for this material. The biochar topic became very popular in last few years, especially the effects of biochar made from various types of biomass on soil properties improvement. Because of this I have chosen the torrefaction process for grass utilization. Energy grasses for the thesis experimental part were obtained from the research station Oseva Pro, Zubří. Production of torrefied carbon from energy grasses, as well as the material pretreatment and analyses, was carried out in the laboratories of IGI (Institute of Geological Engineering), VSB – TU Ostrava. One part of the dissertation thesis was focused on the leaching behavior of the biomass used for the further experiments, where the aim was to determine the effectiveness of biomass treatment prior to its actual application to the soil. The samples were subjected to elemental analysis, RTG – fluorescence and RTG – diffraction to find the chemical and mineralogical composition. Consequently, the biomass properties before and after the torrefaction process were compared. Torrefied grass parameters were compared with IBI Biochar Standars, to determine the suitability / unsuitability of the resulting torrefied product application into the soil. It can be concluded, that torrefied grasses used in this thesis don’t meet the criteria of IBI Biochar Standards. The limits for dioxins and furans are exceeded more than twenty times. Because of this fact it is not possible to apply torrefied grasses to the soil. In the thesis, there are also mentioned the TGA analysis results for the identification of the material energy parameters. Second part of the thesis is focused on the leaching behavior of nutrients and trace elements and sorption ability of torrefied grass in the two matrices: soil and sewage sludge (in form of limed and lime-free sewage sludge). For the research purposes there were used four types of sewage sludges supplied from the Central Waste Water Treatment Plant OVAK a.s., Ostrava – Přívoz. The soil was collected from the Rybí area in Nový Jičín district. The results of the torrefied grass properties were compared to the samples of torrefied wood from Andritz, pyrolysis carbon from MPA Burgau, activated carbon from MERCK Company and pyrolysis carbon from wood produced by the pilot-scale pyrolysis unit of ENET Center, VSB – TU Ostrava. TThe results showed that all carbonaceous materials achieve more than 80 % collection efficiency (sorption) for Cu and Zn. In the case of Zn there was proved higher sorption efficiency for lime-free sewage sludge with all types of carbonaceous materials. For Cu, this dependence was not detected. The highest removal efficiency of dissolved solids was observed for a charcoal MERCK. The pyrolysis carbon from MPA Burgau is unusable for this purpose, because of the chlorides and sulfates extraction which leads to the soil salinization. Torrefied wood from Andritz showed better sorption ability for soluble matter than torrefied grass (leaching of DOC and chloride). From the results obtained using a single sludge and various kinds of sorbents, including activated carbon MERCK, it is not possible to demonstrate that the addition of these sorbents in the sewage sludge significantly affects the nutrition distribution and controlled release. This may be caused due to relatively high concentrations of the Ntot, Ptot and DOC, which are released from the sewage sludge. For the observed carbon sorbents sorption properties verification, it is recommended to make the sorption curves for nutrients, DOC and heavy metals in further research.