Assessment of Migration of PAHs Contained in Soot of Solid Fuel Combustion into the Aquatic Environment

In the thermal processes of fossil fuel and biomass combustion, organic compounds are formed, belonging to the family of so-called Persistent Organic Pollutants. Among them, polycyclic aromatic hydrocarbons (PAHs) are of particular importance. Due to their toxic, mutagenic, and carcinogenic properties, these compounds seriously threaten living organisms. PAHs are formed during the incomplete combustion of organic matter in natural and anthropogenic processes. They are present in soot. Nevertheless, their combustion by-products from individual heat sources are not controlled. They are often used in horticulture or stored in arbitrary places. Collecting or using this waste without determining its toxicity carries the risk of contaminating the land and the water into which the pollutants enter. PAHs pose a severe threat to the aquatic environment as the pollutants contained in the soot are washed away. Therefore, it seemed advisable to conduct research on the combustion of solid fuels such as hard coal with particle sizes above 60 mm, hard coal with a granule size of 25-80 mm, hard coal with a granule size of 8-25 mm, pellets, and mixed firewood. Through the experiments, soot samples were obtained, and a leaching process was performed, thereby extracting eluents from the soot. The results of this work allowed for the determination and assessment of the degree of leachability of polycyclic aromatic hydrocarbons (PAHs) from by-products of combustion of solid fuels, such as soot. The influence of the type of solid fuel burned on the mobility of PAHs in the aquatic environment was determined. The carcinogenicity equivalents of carbon black extracts obtained from the combustion of solid fuels were also determined, as well as the acute toxicity of the tested media by performing biotests using the Microtox kit and Aliivibrio fischeri luminescent bacteria.

Automated summary

During the thermal processes of fossil fuel and biomass combustion, organic compounds called Persistent Organic Pollutants (POPs) are formed, including polycyclic aromatic hydrocarbons (PAHs) that are highly toxic and pose a serious threat to living organisms. The combustion by-products from individual heat sources, such as soot, containing PAHs, are often used or stored without control, leading to potential contamination of land and water. This study conducted research on the combustion of solid fuels and determined the leachability of PAHs from the combustion by-products. The influence of different types of solid fuel on the mobility of PAHs in the aquatic environment was evaluated, and the carcinogenicity and acute toxicity of the combustion by-products were also assessed.