PCDD/F and dioxin-like PCB concentrations during municipal solid waste biomethanation and subsequent composting

• The obtained toxic concentrations in all the fractions were low.
• 2,3,4,7,8-PeCDF, 1,2,3,6,7,8-HxCDD and HpCDD showed the highest toxic concentrations.
• OCDD and 1,2,3,4,6,7,8-HpCDD showed the higher concentrations in almost all samples.
• The contribution of PCBs to the total toxicity is high.

PCDD/F and dioxin-like PCB concentrations were compared in different samples of a municipal solid waste (MSW) treatment plant: the initial MSW fraction that enters the biomethanation from the digester, the semi-solid digestate obtained after biomethanation of MSW, and the solids after composting the digestate since the final product is destined for land application and special attention must be paid to these compounds for environmental considerations. The initial MSW sample showed low concentrations of PCDD/Fs, although in the biomethanation output sample the concentration was more than ten times higher. The difference was even more significant for PCBs. In compost samples concentrations for both PCDD/Fs and PCBs were in the same range as in biomethanation or lower. Nevertheless, concentrations found for all samples were low and these treatments do not pose a major problem for the environment in the working conditions used.