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The main goal of this diploma thesis was studying possible alternative ways of using biochars produced by heating treatment of organic, animal waste. The study was conducted in distinct stages. At first the type and structure of the biochars had to be specified, in the second stage the use of each biochar was examined as adsorbent and finally, in the third stage, their use as a soil fertilizer was tested. For the examination and characterization of biochars, the following analytical techniques were performed with the following order: Total cation exchange capacity (C.E.C) Pore control (BET) Measurements of ζ potential X-ray diffraction (XRD) Scanning electron microscopy (SEM)Energy dispersion spectroscopy (EDS) Elemental analysis of CHNS Determination of the concentration of assimilated trace elements by the DTPA method. Controlling their adsorption capacity was carried out in aqueous solutions with a known concentration of various substances. It was chosen to study the adsorption in a methylene blue solution because as a pigment it is recommended to be used for such an observation. In the same way, the adsorption performance in phenol solutions has been studied, since phenol is a common, dangerous organic pollutant, which is found in both wastewater and water for use, so good removal efficiency would mean that the particular char can also be used for similar purposes. Finally, adsorption in solutions of humic compounds was studied, because humic substances are potentially toxic when they react with metals and organochlorine compounds. Scientific researches have shown that when chlorinating water with a high content of humic compounds, various carcinogenic derivatives known as "disinfecting by-products" can be produced. So if the studied biochars were efficient in the adsorption of the humic compounds, a possible water filtering use could be proposed. Reference curves have been generated for each adsorbed substance and for seven days the adsorption performance was analyzed on a daily basis using the analytical method of ultraviolet- visible spectroscopy (UV-VIS). For the study of their agronomic characteristics and their use as soil improvers, their performance has been checked as soil enriching fertilizers for growing vegetables. Rooting and growth were examined in three plant species and in particular tomatoes, spinach and lettuce. The plantings were carried out in combination of each bio-carbon in proportions of 0, 1:2 & 1:10 with three commercial soil substrates: sand, perlite and peat. From the adsorption study, the best sorbent was found to be the biochar from a tannery waste which had been cracked in anoxic furnace for 12 hours (B12). This biochar showed the largest specific surface area and the most negative ζ potential charge. The charge of the adsorbents was also added, because the adsorption efficiency for methylene blue was around 40%, while for humic was 15% and for phenol 2%. From the statistical test for rooting, the most suitable commercial substrate was peat in combination with biochar B12, probably because it showed a higher concentration of digestible trace minerals than the other two and this gave seed germination. Growth was judged individually for each plant species due to its genetic origin. Tomato and spinach flourished on the peat and had a higher growth rate by adding the biochar from tannery industry waste that was inactivated in the anoxic pyrolytic furnace for 1 hour (B1) in a 1:2 ratio. Lettuce was favored by the addition of biochar B12 to the sand, also in a 1:2 ratio