Influences of temperature, waste size and residence time on the generation of polycyclic aromatic hydrocarbons during the fast pyrolysis of medical waste

Abstract

Mismanagement of Medical wastes can lead to human health and environmental risks. Currently, new pyrolysis technologies are being used to treat medical waste that can reduce the amount of landfilled waste, make it safe, and eventually convert it to a hydrocarbon fuel. Polycyclic aromatic hydrocarbons (PAHs) are pyrolysis by-products and major environmental pollutants. In this study, hazardous medical wastes were pyrolyzed using a semi-industrial pilot scale fast pyrolysis reactor with the purpose of improving the quality of the char for its recovery or use as fuel. The generation of total 4-6 rings PAHs was studied in char product from hazardous medical waste fast pyrolysis under different pyrolysis conditions variables including a vast temperature range (300-700°C), different residence times (100-190 s) and various waste particle sizes (1-3 cm). GC analyzer coupled with a FID detector was used to detect and measure the PAH compounds in char residues. The results demonstrated that the PAHs are present in significant concentrations in char product (54-1184 mg kg-1). Generation of total 4-6 rings PAHs varied by temperature, residence time and waste size. Significant interaction was observed between residence time and temperature that influenced the PAHs generation. By optimizing the pyrolysis operating conditions it is possible to minimize the amount of PAHs generation in the char.