Effect of Composting Ashes from Biomass Combustion on Polycyclic Aromatic Hydrocarbon Content

The safe management of waste from biomass combustion is a global problem, as the use of biomass for energy purposes is increasing around the world. Many rapidly developing countries in Asia, Africa, and South America have weak legal regulations regarding the composition of biomass combustion waste, such as ashes. As a result of the improper management of ashes, some of the pollutants may enter agricultural soils and pose a long-term risk to human health through the accumulation of harmful compounds in food. For this reason, research was carried out on the possibility of reducing harmful contaminants contained in ash in the composting process. The work presents the results of the content of 16 polycyclic aromatic hydrocarbons (PAHs) in the created composts, followed by an analysis of the toxicity, mutagenicity, and carcinogenicity of the created fertilisers. Based on the results obtained, a positive impact of the composting process on the reduction in PAHs contained in ash was found. Composting the mixture at 20 °C resulted in a slight decrease in the ΣPAH16 content from 2185.46 µg∙kg−1 to 2063.48 µg∙kg−1. A greater reduction in ΣPAH16 was obtained in the mixture incubated at 40 °C, where an overall decrease in the ΣPAH16 content was recorded from 2185.46 µg∙kg−1 to 1372.38 µg∙kg−1. The composting process also had a positive impact on the TEQ = CEQ, MEQ, and TCDD-TEQ coefficients, causing their decrease.