The results obtained for the ashes from hard coal and these concerning the examination of biomass ashes, a great diversity can be seen in the physical-chemical characteristics of these ashes. The ashes from the coal are characterized by a greater uniformity of particle size and chemical composition. The ashes from the biomass are characterized by a strong variation of grain size and the composition of individual fractions. The research concerning the ash composition from biomass showed the high content of heavy metals in the ash and excluded the possibility of their use as fertilizers. The test results presented for the ashes both from the hard coal and the biomass have shown that they constitute a waste with high potential for utility and they can be considered as low - cost sorbents to remove contaminants in wastewaters. The ashes from the hard coal and the ashes from biomass showed their efficiency in removing both organic substances and heavy metals.