LEACHING OF POLLUTANTS FROM FLY ASH FROM THE COMBUSTION OF BIOMASS

The biomass is currently one of the main renewable energy sources in the Polish power industry. The use of this fuel results from the current Polish Energy Policy until 2030, which imposes an increase in the share of renewables in final energy consumption to a minimum of 15% by 2020 and a further increase in the subsquent years. The Polish Energy Policy until 2050 assumes that share of renewables in all energy sources will increase to 20%. The biomass can be used as a standalone fuel or can be co-fired with coal. However, as with any solid fuel, the use of biomass in the power industry also generates waste. As with any waste, specific rules on waste management should be defined in the Act on Waste. Energetic waste is widely used in mining, building materials and road construction. Given the long experience in their use, the use of biomass combustion by-products should also be considered. This takes place in the case of fly ashes from co-combustion, which are, for example, compliant with the PN-EN 450: 1 standard "Fly ash for concrete". Fly ash from biomass combustion is different, despite many similarities, from the ashes resulting from coal combustion and co-combustion. The ashes can be characterized by a high leachability of contaminants and thus their economic use may be restricted. The paper presents results of research on the leachability of contaminants from dry fly ashes and their aqueous suspensions. For purposes of comparison, the leachability of contaminants from ashes resulting from the combustion of coal in both conventional and fluidized bed boilers has been determined. The tested ashes from biomass combustion were characterized by a high leachability of sulphates, chlorides, chromium and potassium. Since underground mining remains one of the main directions of the use of fly ash, the obtained results were compared with the PN-G-11011 standard "The materials for solidifying backfill and gob grouting; Requirements and testing, Requirements and testing".