A comprehensive evaluation of the environmental and health risks associated with the potential utilization of chars produced from tires, electro-waste plastics and biomass.

A variety of waste materials are currently being processed using pyrolysis with the objective of valorization, transformation, and conversion into valuable raw materials that can be further utilized. In this work, three different types of char produced from pine sawdust, waste tires and waste from the flat panel display fraction of electrical and electronic equipment were studied. For selection of suitable application, it is necessary to characterize them. The majority of studies focus only on the analysis of the composition and properties of the resulting chars. Nevertheless, the most prevalent utilization of char is in the environment as a soil amendment or adsorbent for the removal of pollutants from water, soil, and air. For this reason, this work incorporated a comprehensive characterization, including an ecotoxicological assessment of the environmental impacts and health risks during their handling/storage. Based on the obtained results and the legislation, a suitable and safe application of the chars was recommended. As presumed, the tested char samples varied in their composition and properties. Biochar from pine sawdust possessed suitable surface properties to be used as a potentially effective adsorbent for water treatment. However, it demonstrated increased ecotoxicity against aquatic organisms, prompting its recommendation for soil application. Waste tires char can be safely used only as an absorbent for air purification due to its high ecotoxicity for aquatic organisms and high PAHs concentration, which disables its soil application. It is inadvisable to utilize char produced from electro-waste plastics in the environment due to its toxic composition, high volatile organic compounds and PAHs content and ecotoxicity. This study confirmed the importance and necessity of using multiple ecotoxicological tests involving different groups of organisms in the characterization of chars (also biochar) to exclude potential negative impacts of their further application.