Change of Polycyclic Aromatic Hydrocarbons During Forced-Aeration Composting of Anaerobic Digested Sludge and Sawdust

The aim of the study was to determine the changes in the polycyclic aromatic hydrocarbons (PAHs) content during the forced-aeration composting of anaerobic digested sludge and sawdust. The content of 16 PAHs and some physical-chemical properties in composting products were monitored. Composting showed an efficient decrease of the content and the bioavailability of individual PAH. The total PAH content (SigmaPAHs) ranged from 7.846 to 1.790 mg/ (kgldrdry sample) for 31 days of composting, and Four- and three-ring compounds were predominant during the composting. Biodegradation and sorption are suggested as the mainly degradation for PAHs with a low number of aromatic rings and PAHs with a large number of aromatic rings, respectively. Concentration, distribution pattern and degradation rate of PAHs in compost product were closely relative with PAHs features in the raw sludge.