Bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in historically contaminated soils after lab incubation with sewage sludge-derived biochars

Biochars reduced the content of Cfree and Cbioacc PAHs in soils. A higher level of reduction was noted for Cfree PAHs than for Cbioacc PAHs. Biochar produced at 700 °C was more effective in the reduction of Cfree and Cbioacc PAHs than biochar produced at 500 °C. It was found that in the soil in which the source of contamination were processes related with the production of bituminous materials (SL-BIT), the effect of reduction of Cfree and Cbioacc was greater than in soil SL-COK where the source of PAHs were coking processes. It also needs to be emphasised that soil SL-BIT, for which better reduction of PAHs was noted, was also characterised by a lower affinity towards those compounds than soil SL-COK.