PAHs emission from cigar burner combustion system and comparison of PAHs content in fly ashes

Agricultural biomass is considered a preferred renewable energy source in Serbia because of its availability and suitability to limit the use of fossil fuel resources and reduce greenhouse gas emissions. Therefore, constant work has been done to develop technologies that enable its utilization for energy purposes. As an example of these efforts, in the Agricultural Corporation PKB, the soybean straw cigarette-type combustion system has been applied for greenhouse heating for over a decade. However, many volatile and semivolatile organic compounds are emitted directly into the atmosphere or concentrated in ash particles during agricultural biomass combustion. Since some of the emitted compounds, such as polycyclic aromatic hydrocarbons (PAHs), are toxic, monitoring their concentrations in fly ash is recommended. Literature data regarding PAHs content in agricultural biomass ashes are insubstantial, especially in Serbia. For that purpose, PAHs contents in the cyclone (CB) and stack (SB) fly ashes of soybean straw were investigated and compared. In addition, the emission factors, toxicity, carcinogenicity and benzo[a]pyrene equivalence concentrations were determined and used to estimate the potential environmental impact of these ashes. As a result, SB ash has been shown to have a higher potential environmental risk than CB ash. Hence, an assessment of using soybean straw as a feed fuel in a real cigarette-type combustion plant regarding PAHs emission is given. These results provide important information for optimizing combustion conditions and assisting the local entities in managing air pollution and control policies in Serbia.